diff --git a/src/app.d.ts b/src/app.d.ts
index 3735081..6040841 100644
--- a/src/app.d.ts
+++ b/src/app.d.ts
@@ -1,6 +1,7 @@
 // See https://kit.svelte.dev/docs/types#app
 // for information about these interfaces
 import MaintenanceProfile from "$entities/MaintenanceProfile.ts";
+import type TagGroup from "$entities/TagGroup.ts";
 
 declare global {
   namespace App {
@@ -24,6 +25,14 @@ declare global {
 
     interface EntityNamesMap {
       profiles: MaintenanceProfile;
+      groups: TagGroup;
+    }
+
+    interface ImageURIs {
+      full: string;
+      large: string;
+      medium: string;
+      small: string;
     }
   }
 }
diff --git a/src/components/features/GroupView.svelte b/src/components/features/GroupView.svelte
new file mode 100644
index 0000000..e984d2a
--- /dev/null
+++ b/src/components/features/GroupView.svelte
@@ -0,0 +1,59 @@
+<script>
+    import TagsColorContainer from "$components/tags/TagsColorContainer.svelte";
+
+    /**
+     * @type {import('$entities/TagGroup.ts').default}
+     */
+    export let group;
+
+    let sortedTagsList, sortedPrefixes;
+
+    $: sortedTagsList = group.settings.tags.sort((a, b) => a.localeCompare(b));
+    $: sortedPrefixes = group.settings.prefixes.sort((a, b) => a.localeCompare(b));
+</script>
+
+<div class="block">
+    <strong>Group Name:</strong>
+    <div>{group.settings.name}</div>
+</div>
+{#if sortedTagsList.length}
+    <div class="block">
+        <strong>Tags:</strong>
+        <TagsColorContainer targetCategory="{group.settings.category}">
+            <div class="tags-list">
+                {#each sortedTagsList as tagName}
+                    <span class="tag">{tagName}</span>
+                {/each}
+            </div>
+        </TagsColorContainer>
+    </div>
+{/if}
+{#if sortedPrefixes.length}
+    <div class="block">
+        <strong>Prefixes:</strong>
+        <TagsColorContainer targetCategory="{group.settings.category}">
+            <div class="tags-list">
+                {#each sortedPrefixes as prefixName}
+                    <span class="tag">{prefixName}*</span>
+                {/each}
+            </div>
+        </TagsColorContainer>
+    </div>
+{/if}
+
+<style lang="scss">
+    .tags-list {
+        display: flex;
+        flex-wrap: wrap;
+        gap: 6px;
+    }
+
+    .block + .block {
+        margin-top: .5em;
+
+        strong {
+            display: block;
+            margin-bottom: .25em;
+        }
+    }
+</style>
diff --git a/src/components/tags/TagsColorContainer.svelte b/src/components/tags/TagsColorContainer.svelte
new file mode 100644
index 0000000..ba02c41
--- /dev/null
+++ b/src/components/tags/TagsColorContainer.svelte
@@ -0,0 +1,62 @@
+<script>
+    /** @type {string} */
+    export let targetCategory = '';
+</script>
+
+<div class="tag-color-container tag-color-container--{targetCategory || 'default'}">
+    <slot></slot>
+</div>
+
+<style lang="scss">
+    @use '../../styles/colors';
+
+    .tag-color-container:is(.tag-color-container--rating) :global(.tag) {
+        background-color: colors.$tag-rating-background;
+        color: colors.$tag-rating-text;
+    }
+
+    .tag-color-container:is(.tag-color-container--spoiler) :global(.tag) {
+        background-color: colors.$tag-spoiler-background;
+        color: colors.$tag-spoiler-text;
+    }
+
+    .tag-color-container:is(.tag-color-container--origin) :global(.tag) {
+        background-color: colors.$tag-origin-background;
+        color: colors.$tag-origin-text;
+    }
+
+    .tag-color-container:is(.tag-color-container--oc) :global(.tag) {
+        background-color: colors.$tag-oc-background;
+        color: colors.$tag-oc-text;
+    }
+
+    .tag-color-container:is(.tag-color-container--error) :global(.tag) {
+        background-color: colors.$tag-error-background;
+        color: colors.$tag-error-text;
+    }
+
+    .tag-color-container:is(.tag-color-container--character) :global(.tag) {
+        background-color: colors.$tag-character-background;
+        color: colors.$tag-character-text;
+    }
+
+    .tag-color-container:is(.tag-color-container--content-official) :global(.tag) {
+        background-color: colors.$tag-content-official-background;
+        color: colors.$tag-content-official-text;
+    }
+
+    .tag-color-container:is(.tag-color-container--content-fanmade) :global(.tag) {
+        background-color: colors.$tag-content-fanmade-background;
+        color: colors.$tag-content-fanmade-text;
+    }
+
+    .tag-color-container:is(.tag-color-container--species) :global(.tag) {
+        background-color: colors.$tag-species-background;
+        color: colors.$tag-species-text;
+    }
+
+    .tag-color-container:is(.tag-color-container--body-type) :global(.tag) {
+        background-color: colors.$tag-body-type-background;
+        color: colors.$tag-body-type-text;
+    }
+</style>
diff --git a/src/components/ui/forms/TagCategorySelectField.svelte b/src/components/ui/forms/TagCategorySelectField.svelte
new file mode 100644
index 0000000..61040ee
--- /dev/null
+++ b/src/components/ui/forms/TagCategorySelectField.svelte
@@ -0,0 +1,80 @@
+<script>
+    import SelectField from "$components/ui/forms/SelectField.svelte";
+    import { categories } from "$lib/booru/tag-categories.js";
+
+    /** @type {string} */
+    export let value = '';
+
+    /** @type {Record<string, string>} */
+    let tagCategoriesOptions = {
+        '': 'Default'
+    };
+
+    tagCategoriesOptions = categories.reduce((options, category) => {
+        options[category] = category
+                .replace('-', ' ')
+                .replace(/(?<=\s|^)\w/g, (matchedCharacter) => matchedCharacter.toUpperCase());
+
+        return options;
+    }, tagCategoriesOptions);
+</script>
+
+<SelectField bind:value={value} options={tagCategoriesOptions} name="tag_color"/>
+
+<style lang="scss">
+    @use '../../../styles/colors';
+
+    :global(select[name=tag_color]) {
+        :global(option) {
+            &:is([value=rating]) {
+                background-color: colors.$tag-rating-background;
+                color: colors.$tag-rating-text;
+            }
+
+            &:is([value=spoiler]) {
+                background-color: colors.$tag-spoiler-background;
+                color: colors.$tag-spoiler-text;
+            }
+
+            &:is([value=origin]) {
+                background-color: colors.$tag-origin-background;
+                color: colors.$tag-origin-text;
+            }
+
+            &:is([value=oc]) {
+                background-color: colors.$tag-oc-background;
+                color: colors.$tag-oc-text;
+            }
+
+            &:is([value=error]) {
+                background-color: colors.$tag-error-background;
+                color: colors.$tag-error-text;
+            }
+
+            &:is([value=character]) {
+                background-color: colors.$tag-character-background;
+                color: colors.$tag-character-text;
+            }
+
+            &:is([value=content-official]) {
+                background-color: colors.$tag-content-official-background;
+                color: colors.$tag-content-official-text;
+            }
+
+            &:is([value=content-fanmade]) {
+                background-color: colors.$tag-content-fanmade-background;
+                color: colors.$tag-content-fanmade-text;
+            }
+
+            &:is([value=species]) {
+                background-color: colors.$tag-species-background;
+                color: colors.$tag-species-text;
+            }
+
+            &:is([value=body-type]) {
+                background-color: colors.$tag-body-type-background;
+                color: colors.$tag-body-type-text;
+            }
+        }
+    }
+</style>
diff --git a/src/lib/booru/tag-categories.js b/src/lib/booru/tag-categories.js
new file mode 100644
index 0000000..cbd33da
--- /dev/null
+++ b/src/lib/booru/tag-categories.js
@@ -0,0 +1,12 @@
+export const categories = [
+  'rating',
+  'spoiler',
+  'origin',
+  'oc',
+  'error',
+  'character',
+  'content-official',
+  'content-fanmade',
+  'species',
+  'body-type',
+];
diff --git a/src/lib/components/FullscreenViewer.js b/src/lib/components/FullscreenViewer.js
index 204f287..ee8b939 100644
--- a/src/lib/components/FullscreenViewer.js
+++ b/src/lib/components/FullscreenViewer.js
@@ -1,13 +1,14 @@
 import {BaseComponent} from "$lib/components/base/BaseComponent.js";
+import MiscSettings from "$lib/extension/settings/MiscSettings.ts";
 
 export class FullscreenViewer extends BaseComponent {
   /** @type {HTMLVideoElement} */
   #videoElement = document.createElement('video');
   /** @type {HTMLImageElement} */
   #imageElement = document.createElement('img');
-
   #spinnerElement = document.createElement('i');
-
+  #sizeSelectorElement = document.createElement('select');
+  #closeButtonElement = document.createElement('i');
   /** @type {number|null} */
   #touchId = null;
   /** @type {number|null} */
@@ -16,15 +17,33 @@ export class FullscreenViewer extends BaseComponent {
   #startY = null;
   /** @type {boolean|null} */
   #isClosingSwipeStarted = null;
+  #isSizeFetched = false;
+  /** @type {App.ImageURIs|null} */
+  #currentURIs = null;
 
   /**
    * @protected
    */
   build() {
     this.container.classList.add('fullscreen-viewer');
-    this.container.append(this.#spinnerElement);
+
+    this.container.append(
+      this.#spinnerElement,
+      this.#sizeSelectorElement,
+      this.#closeButtonElement,
+    );
 
     this.#spinnerElement.classList.add('spinner', 'fa', 'fa-circle-notch', 'fa-spin');
+    this.#closeButtonElement.classList.add('close', 'fa', 'fa-xmark');
+    this.#sizeSelectorElement.classList.add('size-selector', 'input');
+
+    for (const [sizeKey, sizeName] of Object.entries(FullscreenViewer.#previewSizes)) {
+      const sizeOptionElement = document.createElement('option');
+      sizeOptionElement.value = sizeKey;
+      sizeOptionElement.innerText = sizeName;
+
+      this.#sizeSelectorElement.append(sizeOptionElement);
+    }
   }
 
   /**
@@ -40,6 +59,12 @@ export class FullscreenViewer extends BaseComponent {
 
     this.#videoElement.addEventListener('loadeddata', this.#onLoaded.bind(this));
     this.#imageElement.addEventListener('load', this.#onLoaded.bind(this));
+    this.#sizeSelectorElement.addEventListener('click', event => event.stopPropagation());
+
+    FullscreenViewer.#miscSettings
+      .resolveFullscreenViewerPreviewSize()
+      .then(this.#onSizeResolved.bind(this))
+      .then(this.#watchForSizeSelectionChanges.bind(this));
   }
 
   #onLoaded() {
@@ -163,7 +188,49 @@ export class FullscreenViewer extends BaseComponent {
     }
   }
 
+  /**
+   * @param {import("$lib/extension/settings/MiscSettings.js").FullscreenViewerSize} size
+   */
+  #onSizeResolved(size) {
+    this.#sizeSelectorElement.value = size;
+    this.#isSizeFetched = true;
+
+    this.emit('size-loaded');
+  }
+
+  #watchForSizeSelectionChanges() {
+    let lastActiveSize = this.#sizeSelectorElement.value;
+
+    FullscreenViewer.#miscSettings.subscribe(settings => {
+      const targetSize = settings.fullscreenViewerSize;
+
+      if (!targetSize || lastActiveSize === targetSize) {
+        return;
+      }
+
+      lastActiveSize = targetSize;
+      this.#sizeSelectorElement.value = targetSize;
+    });
+
+    this.#sizeSelectorElement.addEventListener('input', () => {
+      const targetSize = this.#sizeSelectorElement.value;
+
+      if (this.#currentURIs) {
+        void this.show(this.#currentURIs);
+      }
+
+      if (!targetSize || targetSize === lastActiveSize || !(targetSize in FullscreenViewer.#previewSizes)) {
+        return;
+      }
+
+      lastActiveSize = targetSize;
+      void FullscreenViewer.#miscSettings.setFullscreenViewerPreviewSize(targetSize);
+    });
+  }
+
   #close() {
+    this.#currentURIs = null;
+
     this.container.classList.remove(FullscreenViewer.#shownState);
     document.body.style.overflow = null;
 
@@ -175,9 +242,44 @@ export class FullscreenViewer extends BaseComponent {
   }
 
   /**
-   * @param {string} url
+   * @param {App.ImageURIs} imageUris
+   * @return {Promise<string|null>}
    */
-  show(url) {
+  async #resolveCurrentSelectedSizeUrl(imageUris) {
+    if (!this.#isSizeFetched) {
+      await new Promise(resolve => this.on('size-loaded', resolve))
+    }
+
+    let targetSize = this.#sizeSelectorElement.value;
+
+    if (!imageUris.hasOwnProperty(targetSize)) {
+      targetSize = FullscreenViewer.#fallbackSize;
+    }
+
+    if (!imageUris.hasOwnProperty(targetSize)) {
+      targetSize = Object.keys(imageUris)[0];
+    }
+
+    if (!targetSize) {
+      return null;
+    }
+
+    return imageUris[targetSize];
+  }
+
+  /**
+   * @param {App.ImageURIs} imageUris
+   */
+  async show(imageUris) {
+    this.#currentURIs = imageUris;
+
+    const url = await this.#resolveCurrentSelectedSizeUrl(imageUris);
+
+    if (!url) {
+      console.warn('Failed to resolve media for the viewer!');
+      return;
+    }
+
     this.container.classList.add('loading');
 
     requestAnimationFrame(() => {
@@ -214,9 +316,23 @@ export class FullscreenViewer extends BaseComponent {
     return url.endsWith('.mp4') || url.endsWith('.webm');
   }
 
+  static #miscSettings = new MiscSettings();
+
   static #offsetProperty = '--offset';
   static #opacityProperty = '--opacity';
   static #shownState = 'shown';
   static #swipeState = 'swiped';
   static #minRequiredDistance = 50;
+
+  /**
+   * @type {Record<import("$lib/extension/settings/MiscSettings.js").FullscreenViewerSize, string>}
+   */
+  static #previewSizes = {
+    full: 'Full',
+    large: 'Large',
+    medium: 'Medium',
+    small: 'Small'
+  }
+
+  static #fallbackSize = 'large';
 }
diff --git a/src/lib/components/ImageShowFullscreenButton.js b/src/lib/components/ImageShowFullscreenButton.js
index f0cd8c7..2f8c6e3 100644
--- a/src/lib/components/ImageShowFullscreenButton.js
+++ b/src/lib/components/ImageShowFullscreenButton.js
@@ -33,7 +33,7 @@ export class ImageShowFullscreenButton extends BaseComponent {
         })
         .then(() => {
           ImageShowFullscreenButton.#miscSettings.subscribe(settings => {
-            this.#isFullscreenButtonEnabled = settings.fullscreenViewer;
+            this.#isFullscreenButtonEnabled = settings.fullscreenViewer ?? true;
             this.#updateFullscreenButtonVisibility();
           })
         })
@@ -47,7 +47,7 @@ export class ImageShowFullscreenButton extends BaseComponent {
   #onButtonClicked() {
     ImageShowFullscreenButton
       .#resolveViewer()
-      .show(this.#mediaBoxTools.mediaBox.imageLinks.large);
+      .show(this.#mediaBoxTools.mediaBox.imageLinks);
   }
 
   /**
diff --git a/src/lib/components/MediaBoxWrapper.js b/src/lib/components/MediaBoxWrapper.js
index cc4c6a2..5fb1a3f 100644
--- a/src/lib/components/MediaBoxWrapper.js
+++ b/src/lib/components/MediaBoxWrapper.js
@@ -56,7 +56,7 @@ export class MediaBoxWrapper extends BaseComponent {
   }
 
   /**
-   * @return {ImageURIs}
+   * @return {App.ImageURIs}
    */
   get imageLinks() {
     return JSON.parse(this.#thumbnailContainer.dataset.uris);
@@ -100,10 +100,3 @@ export function calculateMediaBoxesPositions(mediaBoxesList) {
     }
   })
 }
-
-/**
- * @typedef {Object} ImageURIs
- * @property {string} full
- * @property {string} large
- * @property {string} small
- */
diff --git a/src/lib/components/TagDropdownWrapper.js b/src/lib/components/TagDropdownWrapper.js
index 2ad3d01..a532a15 100644
--- a/src/lib/components/TagDropdownWrapper.js
+++ b/src/lib/components/TagDropdownWrapper.js
@@ -2,10 +2,12 @@ import {BaseComponent} from "$lib/components/base/BaseComponent.js";
 import MaintenanceProfile from "$entities/MaintenanceProfile.ts";
 import MaintenanceSettings from "$lib/extension/settings/MaintenanceSettings.ts";
 import {getComponent} from "$lib/components/base/ComponentUtils.js";
+import CustomCategoriesResolver from "$lib/extension/CustomCategoriesResolver";
 
 const isTagEditorProcessedKey = Symbol();
+const categoriesResolver = new CustomCategoriesResolver();
 
-class TagDropdownWrapper extends BaseComponent {
+export class TagDropdownWrapper extends BaseComponent {
   /**
    * Container with dropdown elements to insert options into.
    * @type {HTMLElement}
@@ -36,6 +38,11 @@ class TagDropdownWrapper extends BaseComponent {
    */
   #isEntered = false;
 
+  /**
+   * @type {string|undefined|null}
+   */
+  #originalCategory = null;
+
   build() {
     this.#dropdownContainer = this.container.querySelector('.dropdown__content');
   }
@@ -53,10 +60,45 @@ class TagDropdownWrapper extends BaseComponent {
     });
   }
 
-  get #tagName() {
+  get tagName() {
     return this.container.dataset.tagName;
   }
 
+  /**
+   * @return {string|undefined}
+   */
+  get tagCategory() {
+    return this.container.dataset.tagCategory;
+  }
+
+  /**
+   * @param {string|undefined} targetCategory
+   */
+  set tagCategory(targetCategory) {
+    // Make sure original category is properly stored.
+    this.originalCategory;
+
+    this.container.dataset.tagCategory = targetCategory;
+
+    if (targetCategory) {
+      this.container.setAttribute('data-tag-category', targetCategory);
+      return;
+    }
+
+    this.container.removeAttribute('data-tag-category');
+  }
+
+  /**
+   * @return {string|undefined}
+   */
+  get originalCategory() {
+    if (this.#originalCategory === null) {
+      this.#originalCategory = this.tagCategory;
+    }
+
+    return this.#originalCategory;
+  }
+
   #onDropdownEntered() {
     this.#isEntered = true;
     this.#updateButtons();
@@ -89,7 +131,7 @@ class TagDropdownWrapper extends BaseComponent {
       const profileName = this.#activeProfile.settings.name;
       let profileSpecificButtonText = `Add to profile "${profileName}"`;
 
-      if (this.#activeProfile.settings.tags.includes(this.#tagName)) {
+      if (this.#activeProfile.settings.tags.includes(this.tagName)) {
         profileSpecificButtonText = `Remove from profile "${profileName}"`;
       }
 
@@ -108,7 +150,7 @@ class TagDropdownWrapper extends BaseComponent {
   async #onAddToNewClicked() {
     const profile = new MaintenanceProfile(crypto.randomUUID(), {
       name: 'Temporary Profile (' + (new Date().toISOString()) + ')',
-      tags: [this.#tagName],
+      tags: [this.tagName],
       temporary: true,
     });
 
@@ -122,7 +164,7 @@ class TagDropdownWrapper extends BaseComponent {
     }
 
     const tagsList = new Set(this.#activeProfile.settings.tags);
-    const targetTagName = this.#tagName;
+    const targetTagName = this.tagName;
 
     if (tagsList.has(targetTagName)) {
       tagsList.delete(targetTagName);
@@ -196,7 +238,10 @@ export function wrapTagDropdown(element) {
     return;
   }
 
-  new TagDropdownWrapper(element).initialize();
+  const tagDropdown = new TagDropdownWrapper(element);
+  tagDropdown.initialize();
+
+  categoriesResolver.addElement(tagDropdown);
 }
 
 export function watchTagDropdownsInTagsEditor() {
diff --git a/src/lib/extension/CustomCategoriesResolver.ts b/src/lib/extension/CustomCategoriesResolver.ts
new file mode 100644
index 0000000..6021939
--- /dev/null
+++ b/src/lib/extension/CustomCategoriesResolver.ts
@@ -0,0 +1,115 @@
+import type {TagDropdownWrapper} from "$lib/components/TagDropdownWrapper";
+import TagGroup from "$entities/TagGroup.ts";
+import {escapeRegExp} from "$lib/utils";
+
+export default class CustomCategoriesResolver {
+  #tagCategories = new Map<string, string>();
+  #compiledRegExps = new Map<RegExp, string>();
+  #tagDropdowns: TagDropdownWrapper[] = [];
+  #lastProcessedIndex = -1;
+  #nextQueuedUpdate = -1;
+
+  constructor() {
+    TagGroup.subscribe(this.#onTagGroupsReceived.bind(this));
+    TagGroup.readAll().then(this.#onTagGroupsReceived.bind(this));
+  }
+
+  public addElement(tagDropdown: TagDropdownWrapper): void {
+    this.#tagDropdowns.push(tagDropdown);
+
+    if (!this.#tagCategories.size && !this.#compiledRegExps.size) {
+      return;
+    }
+
+    this.#queueUpdatingTags();
+  }
+
+  #queueUpdatingTags() {
+    clearTimeout(this.#nextQueuedUpdate);
+
+    this.#nextQueuedUpdate = setTimeout(
+      this.#updateUnprocessedTags.bind(this),
+      CustomCategoriesResolver.#unprocessedTagsTimeout
+    );
+  }
+
+  #updateUnprocessedTags() {
+    const startIndex = Math.max(0, this.#lastProcessedIndex);
+
+    this.#tagDropdowns
+      .slice(startIndex)
+      .filter(CustomCategoriesResolver.#skipTagsWithOriginalCategory)
+      .filter(this.#applyCustomCategoryForExactMatches.bind(this))
+      .filter(this.#matchCustomCategoryByRegExp.bind(this))
+      .forEach(CustomCategoriesResolver.#resetToOriginalCategory);
+  }
+
+  /**
+   * Apply custom categories for the exact tag names.
+   * @param tagDropdown Element to try applying the category for.
+   * @return {boolean} Will return false when tag is processed and true when it is not found.
+   * @private
+   */
+  #applyCustomCategoryForExactMatches(tagDropdown: TagDropdownWrapper): boolean {
+    const tagName = tagDropdown.tagName!;
+
+    if (!this.#tagCategories.has(tagName)) {
+      return true;
+    }
+
+    tagDropdown.tagCategory = this.#tagCategories.get(tagName)!;
+    return false;
+  }
+
+  #matchCustomCategoryByRegExp(tagDropdown: TagDropdownWrapper) {
+    const tagName = tagDropdown.tagName!;
+
+    for (const targetRegularExpression of this.#compiledRegExps.keys()) {
+      if (!targetRegularExpression.test(tagName)) {
+        continue;
+      }
+
+      tagDropdown.tagCategory = this.#compiledRegExps.get(targetRegularExpression)!;
+      return false;
+    }
+
+    return true;
+  }
+
+  #onTagGroupsReceived(tagGroups: TagGroup[]) {
+    this.#tagCategories.clear();
+    this.#compiledRegExps.clear();
+    this.#lastProcessedIndex = -1;
+
+    if (!tagGroups.length) {
+      return;
+    }
+
+    for (const tagGroup of tagGroups) {
+      const categoryName = tagGroup.settings.category;
+
+      for (const tagName of tagGroup.settings.tags) {
+        this.#tagCategories.set(tagName, categoryName);
+      }
+
+      for (const tagPrefix of tagGroup.settings.prefixes) {
+        this.#compiledRegExps.set(
+          new RegExp(`^${escapeRegExp(tagPrefix)}`),
+          categoryName
+        );
+      }
+    }
+
+    this.#queueUpdatingTags();
+  }
+
+  static #skipTagsWithOriginalCategory(tagDropdown: TagDropdownWrapper): boolean {
+    return !tagDropdown.originalCategory;
+  }
+
+  static #resetToOriginalCategory(tagDropdown: TagDropdownWrapper): void {
+    tagDropdown.tagCategory = tagDropdown.originalCategory;
+  }
+
+  static #unprocessedTagsTimeout = 0;
+}
diff --git a/src/lib/extension/entities/TagGroup.ts b/src/lib/extension/entities/TagGroup.ts
new file mode 100644
index 0000000..95dc44a
--- /dev/null
+++ b/src/lib/extension/entities/TagGroup.ts
@@ -0,0 +1,21 @@
+import StorageEntity from "$lib/extension/base/StorageEntity.ts";
+
+export interface TagGroupSettings {
+  name: string;
+  tags: string[];
+  prefixes: string[];
+  category: string;
+}
+
+export default class TagGroup extends StorageEntity<TagGroupSettings> {
+  constructor(id: string, settings: Partial<TagGroupSettings>) {
+    super(id, {
+      name: settings.name || '',
+      tags: settings.tags || [],
+      prefixes: settings.prefixes || [],
+      category: settings.category || ''
+    });
+  }
+
+  static _entityName = 'groups';
+}
diff --git a/src/lib/extension/settings/MiscSettings.ts b/src/lib/extension/settings/MiscSettings.ts
index 94ea7d2..1e0e76d 100644
--- a/src/lib/extension/settings/MiscSettings.ts
+++ b/src/lib/extension/settings/MiscSettings.ts
@@ -1,7 +1,10 @@
 import CacheableSettings from "$lib/extension/base/CacheableSettings.ts";
 
+export type FullscreenViewerSize = 'small' | 'medium' | 'large' | 'full';
+
 interface MiscSettingsFields {
   fullscreenViewer: boolean;
+  fullscreenViewerSize: FullscreenViewerSize;
 }
 
 export default class MiscSettings extends CacheableSettings<MiscSettingsFields> {
@@ -13,7 +16,15 @@ export default class MiscSettings extends CacheableSettings<MiscSettingsFields>
     return this._resolveSetting("fullscreenViewer", true);
   }
 
+  async resolveFullscreenViewerPreviewSize() {
+    return this._resolveSetting('fullscreenViewerSize', 'large');
+  }
+
   async setFullscreenViewerEnabled(isEnabled: boolean) {
     return this._writeSetting("fullscreenViewer", isEnabled);
   }
+
+  async setFullscreenViewerPreviewSize(size: FullscreenViewerSize | string) {
+    return this._writeSetting('fullscreenViewerSize', size as FullscreenViewerSize);
+  }
 }
diff --git a/src/lib/extension/transporting/exporters.ts b/src/lib/extension/transporting/exporters.ts
index c2386c4..468df8e 100644
--- a/src/lib/extension/transporting/exporters.ts
+++ b/src/lib/extension/transporting/exporters.ts
@@ -13,6 +13,15 @@ const entitiesExporters: ExportersMap = {
       tags: entity.settings.tags,
     }
   },
+  groups: entity => {
+    return {
+      v: 1,
+      id: entity.id,
+      name: entity.settings.name,
+      tags: entity.settings.tags,
+      prefixes: entity.settings.prefixes,
+    }
+  }
 };
 
 export function exportEntityToObject(entityInstance: StorageEntity<any>, entityName: string): Record<string, any> {
diff --git a/src/lib/utils.js b/src/lib/utils.js
index db17ea5..c7a6531 100644
--- a/src/lib/utils.js
+++ b/src/lib/utils.js
@@ -21,3 +21,23 @@ export function findDeepObject(targetObject, path) {
 
   return result;
 }
+
+/**
+ * Matches all the characters needing replacement.
+ *
+ * Gathered from right here: https://stackoverflow.com/a/3561711/16048617. Because I don't want to introduce some
+ * library for that.
+ *
+ * @type {RegExp}
+ */
+const unsafeRegExpCharacters = /[/\-\\^$*+?.()|[\]{}]/g;
+
+/**
+ * Escape all the RegExp syntax-related characters in the following value.
+ * @param {string} value Original value.
+ * @return {string} Resulting value with all needed characters escaped.
+ */
+export function escapeRegExp(value) {
+  unsafeRegExpCharacters.lastIndex = 0;
+  return value.replace(unsafeRegExpCharacters, "\\$&");
+}
diff --git a/src/routes/+page.svelte b/src/routes/+page.svelte
index 7b1fa3a..49cdecb 100644
--- a/src/routes/+page.svelte
+++ b/src/routes/+page.svelte
@@ -22,6 +22,7 @@
         <hr>
     {/if}
     <MenuItem href="/features/maintenance">Tagging Profiles</MenuItem>
+    <MenuItem href="/features/groups">Tag Groups</MenuItem>
     <hr>
     <MenuItem href="/preferences">Preferences</MenuItem>
     <MenuItem href="/about">About</MenuItem>
diff --git a/src/routes/features/groups/+page.svelte b/src/routes/features/groups/+page.svelte
new file mode 100644
index 0000000..97fc1b7
--- /dev/null
+++ b/src/routes/features/groups/+page.svelte
@@ -0,0 +1,23 @@
+<script>
+    import Menu from "$components/ui/menu/Menu.svelte";
+    import MenuItem from "$components/ui/menu/MenuItem.svelte";
+    import { tagGroupsStore } from "$stores/tag-groups-store.js";
+
+    /** @type {import('$entities/TagGroup.ts').default[]} */
+    let groups = [];
+
+    $: groups = $tagGroupsStore.sort((a, b) => a.settings.name.localeCompare(b.settings.name));
+</script>
+
+<Menu>
+    <MenuItem href="/" icon="arrow-left">Back</MenuItem>
+    <MenuItem href="/features/groups/new/edit" icon="plus">Create New</MenuItem>
+    {#if groups.length}
+        <hr>
+        {#each groups as group}
+            <MenuItem href="/features/groups/{group.id}">{group.settings.name}</MenuItem>
+        {/each}
+    {/if}
+    <hr>
+    <MenuItem href="/features/groups/import">Import Group</MenuItem>
+</Menu>
diff --git a/src/routes/features/groups/[id]/+page.svelte b/src/routes/features/groups/[id]/+page.svelte
new file mode 100644
index 0000000..fffcfdb
--- /dev/null
+++ b/src/routes/features/groups/[id]/+page.svelte
@@ -0,0 +1,39 @@
+<script>
+    import { goto } from "$app/navigation";
+    import { page } from "$app/stores";
+    import GroupView from "$components/features/GroupView.svelte";
+    import Menu from "$components/ui/menu/Menu.svelte";
+    import MenuItem from "$components/ui/menu/MenuItem.svelte";
+    import { tagGroupsStore } from "$stores/tag-groups-store.js";
+
+    const groupId = $page.params.id;
+    /** @type {import('$entities/TagGroup.ts').default|null} */
+    let group = null;
+
+    if (groupId==='new') {
+        goto('/features/groups/new/edit');
+    }
+
+    $: {
+        group = $tagGroupsStore.find(group => group.id===groupId) || null;
+
+        if (!group) {
+            console.warn(`Group ${ groupId } not found.`);
+            goto('/features/groups');
+        }
+    }
+</script>
+
+<Menu>
+    <MenuItem href="/features/groups" icon="arrow-left">Back</MenuItem>
+    <hr>
+</Menu>
+{#if group}
+    <GroupView {group}/>
+{/if}
+<Menu>
+    <hr>
+    <MenuItem href="/features/groups/{groupId}/edit" icon="wrench">Edit Group</MenuItem>
+    <MenuItem href="/features/groups/{groupId}/export" icon="file-export">Export Group</MenuItem>
+    <MenuItem href="/features/groups/{groupId}/delete" icon="trash">Delete Group</MenuItem>
+</Menu>
diff --git a/src/routes/features/groups/[id]/delete/+page.svelte b/src/routes/features/groups/[id]/delete/+page.svelte
new file mode 100644
index 0000000..50f1b1b
--- /dev/null
+++ b/src/routes/features/groups/[id]/delete/+page.svelte
@@ -0,0 +1,41 @@
+<script>
+    import { goto } from "$app/navigation";
+    import { page } from "$app/stores";
+    import Menu from "$components/ui/menu/Menu.svelte";
+    import MenuItem from "$components/ui/menu/MenuItem.svelte";
+    import { tagGroupsStore } from "$stores/tag-groups-store.js";
+
+    const groupId = $page.params.id;
+    const targetGroup = $tagGroupsStore.find(group => group.id===groupId);
+
+    if (!targetGroup) {
+        void goto('/features/groups');
+    }
+
+    async function deleteGroup() {
+        if (!targetGroup) {
+            console.warn('Attempting to delete the group, but the group is not loaded yet.');
+            return;
+        }
+
+        await targetGroup.delete();
+        await goto('/features/groups');
+    }
+</script>
+
+<Menu>
+    <MenuItem icon="arrow-left" href="/features/groups/{groupId}">Back</MenuItem>
+    <hr>
+</Menu>
+{#if targetGroup}
+    <p>
+        Do you want to remove group "{targetGroup.settings.name}"? This action is irreversible.
+    </p>
+    <Menu>
+        <hr>
+        <MenuItem on:click={deleteGroup}>Yes</MenuItem>
+        <MenuItem href="/features/groups/{groupId}">No</MenuItem>
+    </Menu>
+{:else}
+    <p>Loading...</p>
+{/if}
diff --git a/src/routes/features/groups/[id]/edit/+page.svelte b/src/routes/features/groups/[id]/edit/+page.svelte
new file mode 100644
index 0000000..746c79d
--- /dev/null
+++ b/src/routes/features/groups/[id]/edit/+page.svelte
@@ -0,0 +1,82 @@
+<script>
+    import {goto} from "$app/navigation";
+    import {page} from "$app/stores";
+    import TagsColorContainer from "$components/tags/TagsColorContainer.svelte";
+    import FormContainer from "$components/ui/forms/FormContainer.svelte";
+    import FormControl from "$components/ui/forms/FormControl.svelte";
+    import TagCategorySelectField from "$components/ui/forms/TagCategorySelectField.svelte";
+    import TextField from "$components/ui/forms/TextField.svelte";
+    import Menu from "$components/ui/menu/Menu.svelte";
+    import MenuItem from "$components/ui/menu/MenuItem.svelte";
+    import TagsEditor from "$components/web-components/TagsEditor.svelte";
+    import TagGroup from "$entities/TagGroup.ts";
+    import {tagGroupsStore} from "$stores/tag-groups-store.js";
+
+    const groupId = $page.params.id;
+    /** @type {TagGroup|null} */
+    let targetGroup = null;
+
+    let groupName = '';
+    /** @type {string[]} */
+    let tagsList = [];
+    /** @type {string[]} */
+    let prefixesList = [];
+    let tagCategory = '';
+
+    if (groupId==='new') {
+        targetGroup = new TagGroup(crypto.randomUUID(), {});
+    } else {
+        targetGroup = $tagGroupsStore.find(group => group.id===groupId) || null;
+
+        if (targetGroup) {
+            groupName = targetGroup.settings.name;
+            tagsList = [...targetGroup.settings.tags].sort((a, b) => a.localeCompare(b));
+            prefixesList = [...targetGroup.settings.prefixes].sort((a, b) => a.localeCompare(b));
+            tagCategory = targetGroup.settings.category;
+        } else {
+            goto('/features/groups');
+        }
+    }
+
+    async function saveGroup() {
+        if (!targetGroup) {
+            console.warn('Attempting to save group, but group is not loaded yet.');
+            return;
+        }
+
+        targetGroup.settings.name = groupName;
+        targetGroup.settings.tags = [...tagsList];
+        targetGroup.settings.prefixes = [...prefixesList];
+        targetGroup.settings.category = tagCategory;
+
+        await targetGroup.save();
+        await goto(`/features/groups/${targetGroup.id}`);
+    }
+</script>
+
+<Menu>
+    <MenuItem href="/features/groups/${groupId}" icon="arrow-left">Back</MenuItem>
+    <hr>
+</Menu>
+<FormContainer>
+    <FormControl label="Group Name">
+        <TextField bind:value={groupName} placeholder="Group Name"></TextField>
+    </FormControl>
+    <FormControl label="Group Color">
+        <TagCategorySelectField bind:value={tagCategory}/>
+    </FormControl>
+    <TagsColorContainer targetCategory="{tagCategory}">
+        <FormControl label="Tags">
+            <TagsEditor bind:tags={tagsList}/>
+        </FormControl>
+    </TagsColorContainer>
+    <TagsColorContainer targetCategory="{tagCategory}">
+        <FormControl label="Tag Prefixes">
+            <TagsEditor bind:tags={prefixesList}/>
+        </FormControl>
+    </TagsColorContainer>
+</FormContainer>
+<Menu>
+    <hr>
+    <MenuItem on:click={saveGroup}>Save Group</MenuItem>
+</Menu>
diff --git a/src/routes/features/groups/[id]/export/+page.svelte b/src/routes/features/groups/[id]/export/+page.svelte
new file mode 100644
index 0000000..1a2b891
--- /dev/null
+++ b/src/routes/features/groups/[id]/export/+page.svelte
@@ -0,0 +1,50 @@
+<script>
+    import { goto } from "$app/navigation";
+    import { page } from "$app/stores";
+    import FormContainer from "$components/ui/forms/FormContainer.svelte";
+    import FormControl from "$components/ui/forms/FormControl.svelte";
+    import Menu from "$components/ui/menu/Menu.svelte";
+    import MenuItem from "$components/ui/menu/MenuItem.svelte";
+    import TagGroup from "$entities/TagGroup.ts";
+    import EntitiesTransporter from "$lib/extension/EntitiesTransporter.ts";
+    import { tagGroupsStore } from "$stores/tag-groups-store.js";
+
+    const groupId = $page.params.id;
+    const groupTransporter = new EntitiesTransporter(TagGroup);
+    const group = $tagGroupsStore.find(group => group.id===groupId);
+
+    /** @type {string} */
+    let rawExportedGroup;
+    /** @type {string} */
+    let encodedExportedGroup;
+
+    if (!group) {
+        goto('/features/groups');
+    } else {
+        rawExportedGroup = groupTransporter.exportToJSON(group);
+        encodedExportedGroup = groupTransporter.exportToCompressedJSON(group);
+    }
+
+    let isEncodedGroupShown = true;
+</script>
+
+<Menu>
+    <MenuItem href="/features/groups/{groupId}" icon="arrow-left">Back</MenuItem>
+    <hr>
+</Menu>
+<FormContainer>
+    <FormControl label="Export string">
+        <textarea readonly rows="6">{isEncodedGroupShown ? encodedExportedGroup : rawExportedGroup}</textarea>
+    </FormControl>
+</FormContainer>
+<Menu>
+    <hr>
+    <MenuItem on:click={() => isEncodedGroupShown = !isEncodedGroupShown}>
+        Switch Format:
+        {#if isEncodedGroupShown}
+            Base64-Encoded
+        {:else}
+            Raw JSON
+        {/if}
+    </MenuItem>
+</Menu>
diff --git a/src/routes/features/groups/import/+page.svelte b/src/routes/features/groups/import/+page.svelte
new file mode 100644
index 0000000..01583bc
--- /dev/null
+++ b/src/routes/features/groups/import/+page.svelte
@@ -0,0 +1,134 @@
+<script>
+    import { goto } from "$app/navigation";
+    import GroupView from "$components/features/GroupView.svelte";
+    import FormContainer from "$components/ui/forms/FormContainer.svelte";
+    import FormControl from "$components/ui/forms/FormControl.svelte";
+    import Menu from "$components/ui/menu/Menu.svelte";
+    import MenuItem from "$components/ui/menu/MenuItem.svelte";
+    import TagGroup from "$entities/TagGroup.ts";
+    import EntitiesTransporter from "$lib/extension/EntitiesTransporter.ts";
+    import { tagGroupsStore } from "$stores/tag-groups-store.js";
+
+    const groupTransporter = new EntitiesTransporter(TagGroup);
+
+    /** @type {string} */
+    let importedString = '';
+    /** @type {string} */
+    let errorMessage = '';
+
+    /** @type {TagGroup|null} */
+    let candidateGroup = null;
+    /** @type {TagGroup|null} */
+    let existingGroup = null;
+
+    function tryImportingGroup() {
+        candidateGroup = null;
+        existingGroup = null;
+
+        errorMessage = '';
+        importedString = importedString.trim();
+
+        if (!importedString) {
+            errorMessage = 'Nothing to import.';
+            return;
+        }
+
+        try {
+            if (importedString.trim().startsWith('{')) {
+                candidateGroup = groupTransporter.importFromJSON(importedString);
+            }
+
+            candidateGroup = groupTransporter.importFromCompressedJSON(importedString);
+        } catch (error) {
+            errorMessage = error instanceof Error
+                    ? error.message
+                    :'Unknown error';
+        }
+
+        if (candidateGroup) {
+            existingGroup = $tagGroupsStore.find(group => group.id===candidateGroup?.id) ?? null;
+        }
+    }
+
+    function saveGroup() {
+        if (!candidateGroup) {
+            return;
+        }
+
+        candidateGroup.save().then(() => {
+            goto(`/features/groups`);
+        });
+    }
+
+    function cloneAndSaveGroup() {
+        if (!candidateGroup) {
+            return;
+        }
+
+        const clonedProfile = new TagGroup(crypto.randomUUID(), candidateGroup.settings);
+        clonedProfile.settings.name += ` (Clone ${ new Date().toISOString() })`;
+        clonedProfile.save().then(() => {
+            goto(`/features/groups`);
+        });
+    }
+</script>
+
+<Menu>
+    <MenuItem icon="arrow-left" href="/features/groups">Back</MenuItem>
+    <hr>
+</Menu>
+{#if errorMessage}
+    <p class="error">Failed to import: {errorMessage}</p>
+    <Menu>
+        <hr>
+    </Menu>
+{/if}
+{#if !candidateGroup}
+    <FormContainer>
+        <FormControl label="Import string">
+            <textarea bind:value={importedString} rows="6"></textarea>
+        </FormControl>
+    </FormContainer>
+    <Menu>
+        <hr>
+        <MenuItem on:click={tryImportingGroup}>Import</MenuItem>
+    </Menu>
+{:else}
+    {#if existingGroup}
+        <p class="warning">
+            This group will replace the existing "{existingGroup.settings.name}" group, since it have the same ID.
+        </p>
+    {/if}
+    <GroupView group="{candidateGroup}"></GroupView>
+    <Menu>
+        <hr>
+        {#if existingGroup}
+            <MenuItem on:click={saveGroup}>Replace Existing Group</MenuItem>
+            <MenuItem on:click={cloneAndSaveGroup}>Save as New Group</MenuItem>
+        {:else}
+            <MenuItem on:click={saveGroup}>Import New Group</MenuItem>
+        {/if}
+        <MenuItem on:click={() => candidateGroup = null}>Cancel</MenuItem>
+    </Menu>
+{/if}
+
+<style lang="scss">
+    @use '../../../../styles/colors';
+
+    .error, .warning {
+        padding: 5px 24px;
+        margin: {
+            left: -24px;
+            right: -24px;
+        }
+    }
+
+    .error {
+        background: colors.$error-background;
+    }
+
+    .warning {
+        background: colors.$warning-background;
+        margin-bottom: .5em;
+    }
+</style>
diff --git a/src/stores/tag-groups-store.js b/src/stores/tag-groups-store.js
new file mode 100644
index 0000000..057becd
--- /dev/null
+++ b/src/stores/tag-groups-store.js
@@ -0,0 +1,12 @@
+import {writable} from "svelte/store";
+import TagGroup from "$entities/TagGroup.ts";
+
+/** @type {import('svelte/store').Writable<TagGroup[]>} */
+export const tagGroupsStore = writable([]);
+
+TagGroup
+  .readAll()
+  .then(groups => tagGroupsStore.set(groups))
+  .then(() => {
+    TagGroup.subscribe(groups => tagGroupsStore.set(groups));
+  });
diff --git a/src/styles/content/listing.scss b/src/styles/content/listing.scss
index 37804f5..a6ec9e9 100644
--- a/src/styles/content/listing.scss
+++ b/src/styles/content/listing.scss
@@ -199,6 +199,30 @@
     transition: opacity .25s ease;
   }
 
+  .size-selector {
+    position: absolute;
+    top: 5px;
+    left: 5px;
+    z-index: 1;
+  }
+
+  .close {
+    position: absolute;
+    top: 5px;
+    right: 5px;
+    z-index: 1;
+    padding: 5px;
+    background-color: colors.$text;
+    color: colors.$background;
+    font-size: 20px;
+    line-height: 20px;
+    width: 20px;
+    height: 20px;
+    text-align: center;
+    display: block;
+    cursor: pointer;
+  }
+
   &.shown {
     opacity: var(--opacity, 1);
     pointer-events: initial;