diff --git a/app/changelog/page.mdx b/app/changelog/page.mdx
index 3916255..b350707 100644
--- a/app/changelog/page.mdx
+++ b/app/changelog/page.mdx
@@ -22,7 +22,7 @@ This page lists changes since Working Draft 03. {{ className: 'lead' }}
 - Added shared inboxes.
 - Added `remote` field to [ContentFormat](/structures/content-format).
 - Switched to [ThumbHash](https://evanw.github.io/thumbhash/) from [BlurHash](https://blurha.sh/).
-- Added optional identification characters to [Custom Emojis](/structures/emoji).
+- Added identification characters to [Custom Emojis](/structures/emoji).
 - Added `manually_approves_followers` to [Users](/entities/user).
 - Removed `visibility` from [Notes](/entities/note).
 - Made `subject` optional in [Notes](/entities/note).
diff --git a/app/extensions/custom-emojis/page.mdx b/app/extensions/custom-emojis/page.mdx
new file mode 100644
index 0000000..867a166
--- /dev/null
+++ b/app/extensions/custom-emojis/page.mdx
@@ -0,0 +1,79 @@
+export const metadata = {
+    title: "Custom Emojis Extension",
+    description: "The Custom Emojis extension adds support for custom emojis in notes.",
+}
+
+# Custom Emojis Extension
+
+The Custom Emojis extension adds support for adding personalized emojis to federated data. {{ className: 'lead' }}
+
+## Rendering
+
+To render custom emojis, clients **should** perform the following steps:
+1. Find all instances of custom emoji names in the text content.
+2. Replace the custom emoji names with the corresponding emoji images in text.
+
+If custom emojis are not supported, clients **should** leave the custom emoji names as-is. Images **should** have any associated `alt` text for accessibility.
+
+```html {{ 'title': 'Example HTML/CSS' }}
+<style>
+img.emoji {
+    display: inline;
+    height: 1em;
+}
+</style>
+
+<p>
+    Hello, world! <img src="https://cdn.example.com/emojis/happy_face.webp" alt="A happy emoji smiling." class="emoji" />!
+</p>
+```
+
+Emojis **should** be displayed at a fixed height (such as `1em`), but their width **should** be allowed to be flexible.
+
+## Extension Definition
+
+Custom Emojis can be added to any entity with text content. The extension ID is `pub.versia:custom_emojis`.
+
+<Row>
+    <Col>
+        <Properties>
+            <Property name="emojis" type="CustomEmoji[]" required={true} typeLink="/structures/emoji">
+                [Custom emojis](/structures/emoji) to be added to the note.
+            </Property>
+        </Properties>
+    </Col>
+
+    <Col sticky>
+
+    ```jsonc {{ 'title': 'Example Usage' }}
+    {
+        "id": "456df8ed-daf1-4062-abab-491071c7b8dd",
+        "type": "Note",
+        "uri": "https://versia.social/notes/456df8ed-daf1-4062-abab-491071c7b8dd",
+        "created_at": "2024-04-09T01:38:51.743Z",
+        "content": {
+            "text/plain": {
+                "content": "Hello, world :happy_face:!"
+            }
+        },
+        "extensions": { // [!code focus:16]
+            "pub.versia:custom_emojis": {
+                "emojis": [
+                    {
+                        "name": ":happy_face:",
+                        "content": {
+                            "image/webp": {
+                                "content": "https://cdn.example.com/emojis/happy_face.webp",
+                                "remote": true,
+                                "description": "A happy emoji smiling.",
+                            }
+                        }
+                    }
+                ]
+            }
+        }
+    }
+    ```
+
+    </Col>
+</Row>
\ No newline at end of file
diff --git a/app/extensions/page.mdx b/app/extensions/page.mdx
index 82583cc..05cc9d4 100644
--- a/app/extensions/page.mdx
+++ b/app/extensions/page.mdx
@@ -21,7 +21,7 @@ Extensions **must not** be designed in a way that makes them required to underst
 
 Versia extension names are composed of two parts:
 - The domain name of the extension author, in reverse order. Example: `pub.versia`
-- The extension name, separated by a colon. Example: `likes`
+- The extension name, separated by a colon. `snake_case`. Example: `likes`
 
 ``` {{ title: "Example Extension Name" }}
 pub.versia:likes
@@ -30,7 +30,7 @@ pub.versia:likes
 ### Custom entities
 
 Custom entities are named in the same way, but with an additional part:
-- The entity name, separated by a slash. PascalCase. Example: `Like`
+- The entity name, separated by a slash. `PascalCase`. Example: `Like`
 
 ``` {{ title: "Example Custom Entity Type" }}
 pub.versia:likes/Like
diff --git a/app/structures/emoji/page.mdx b/app/structures/emoji/page.mdx
index f3ebeb1..078c8cf 100644
--- a/app/structures/emoji/page.mdx
+++ b/app/structures/emoji/page.mdx
@@ -17,11 +17,11 @@ export const metadata = {
     <Col>
         <Properties>
             <Property name="name" type="string" required={true}>
-                Emoji name, optionally surrounded by identification characters (for example, colons: `:happy_face:`).
+                Emoji name, surrounded by identification characters (for example, colons: `:happy_face:`).
 
                 Name must match the regex `^[a-zA-Z0-9_-]+$`.
                 
-                Identification characters must not match the name regex (must not be alphanumeric/underscore/hyphen).
+                Identification characters must not match the name regex (must not be alphanumeric/underscore/hyphen). There may only be two identification characters, one at the beginning and one at the end.
             </Property>
             <Property name="content" type="ContentFormat" required={true} typeLink="/structures/content-format">
                 Emoji content. Must be an image format (`image/*`).
diff --git a/components/Navigation.tsx b/components/Navigation.tsx
index 522dae7..46cbd65 100644
--- a/components/Navigation.tsx
+++ b/components/Navigation.tsx
@@ -287,6 +287,7 @@ export const navigation: NavGroup[] = [
     {
         title: "Extensions",
         links: [
+            { title: "Custom Emojis", href: "/extensions/custom-emojis" },
             { title: "Likes", href: "/extensions/likes" },
             { title: "Vanity", href: "/extensions/vanity" },
             { title: "WebSockets", href: "/extensions/websockets" },