Main Concepts

ActivityPub: The protocol used by most Fediverse platforms to enable communication between servers. A W3C standard that defines how servers exchange posts, follows, likes etc.

Federation: The ability of different servers (instances) to communicate and share content with each other, allowing users on different platforms to interact seamlessly. Similar to how email works across different providers.

Fediverse: A portmanteau of “federation” and “universe” – refers to the collection of federated social networks that can communicate with each other using the ActivityPub protocol. The ‘Fedi’ is a decentralized alternative to traditional social media platforms.

Instance: An individual server running Fediverse software. Each instance operates independently with its own rules, moderation, and culture, but can communicate with other instances through federation.

User Actions & Features

Alt Text: Descriptive text added to images to make them accessible to visually impaired users and those using adaptive technology – eg. screen readers. The Mastodon community strongly encourages the use of Alt-Text.

Boost: The Fedi equivalent of a “retweet” or “reshare.” Boosting makes a post appear on your profile and in your followers’ feeds.

CW (Content Warning): A feature that allows users to hide post content behind a warning label, letting others choose whether to view potentially sensitive material.

Direct Message (DM): A post visible only to mentioned users. Privacy levels may vary by platform implementation. Please note: Both Mastodon and PixelFed are NOT secure platforms. You should use other communication tools if you require privacy.

Favorite/Like: Showing appreciation for a post. Although these don’t impact an algorithm or register a ‘count’ they are highly encouraged, as they help users feel ‘seen’ on the timeline.

Hashtag: A word or phrase preceded by # used to categorize content and make it discoverable. Hashtags are a primary discovery mechanism in the Fediverse.

Mention: Tagging another user in a post using their handle (e.g., @us******@******ce.social). This notifies them and creates a link to their profile.

Toot: Originally the name for a post on Mastodon (like Twitter’s “tweet”). While still used colloquially, many also just say “post.”

Fediverse Platforms

Bookwyrm: A social reading and book cataloging platform, similar to Goodreads.

Friendica: A general-purpose social networking platform with Facebook-like features.

Kbin/Mbin: A Reddit-like platform that federates with Lemmy and Mastodon.

Lemmy: A Reddit-like link aggregation and discussion platform.

Mastodon: The most popular Fediverse platform, similar to Twitter/X in format. Features character limits (usually 500), content warnings, and robust moderation tools.

Misskey/Firefish: Microblogging platforms with different features and aesthetics compared to Mastodon, popular in Japan.

PeerTube: A federated video hosting platform, similar to YouTube.

Pixelfed: An Instagram-like photo sharing platform in the Fediverse.

WriteFreely: A minimalist, federated blogging platform.

Community & Culture

Fediblock: A hashtag used to warn other instance admins about problematic instances or users that should be considered for blocking.

Instance Admin: The person or team responsible for running and maintaining an instance, including server management and high-level moderation decisions.

Moderator: Someone who helps enforce community guidelines and handles reports of problematic content or behavior.

Reply Guy: Someone who excessively replies to posts, often in unwelcome or pedantic ways. Generally considered poor Fediverse etiquette.

Privacy & Moderation

Followers-Only Post: Only visible to approved followers.

Limited/Silenced: When an instance limits another instance, preventing its posts from appearing in public timelines while still allowing follows.

Public Post: Visible to everyone and appears in public timelines.

Report: A mechanism to alert moderators about content or behavior that violates instance rules.

Suspended/Blocked: Complete blocking of an instance or user, preventing all interaction.

Unlisted Post: Visible to everyone but doesn’t appear in public timelines; must be accessed directly or through boosts.