Mastodon is a free, open-source social network made of independently run servers that talk to each other over the ActivityPub protocol. Eugen Rochko first released it in 2016, and people on different servers can follow one another.
Mastodon is one of the best-known members of the fediverse, and this guide covers how its servers work, what the culture is like and how to get started.
How Mastodon works
Mastodon does not live on one website. Users join a specific server, often called an instance, rather than a single centralized website or application, according to Wikipedia’s entry on the platform. Each server has its own moderators, rules and community, yet all of them can exchange posts.
The official documentation describes this as federation, a form of decentralization. It lists email, XMPP and phone networks as federated systems, and Twitter, Facebook and Instagram as centralized ones. A Mastodon website can also operate alone, without connecting to others, per the Mastodon documentation.
Federation works because Mastodon uses a standardized, open protocol called ActivityPub. Any software that implements ActivityPub can communicate with Mastodon in the same way that Mastodon servers communicate with each other. That is why a federated social network can include very different programs, and why alternatives such as Pleroma can exchange posts with Mastodon users.
Choosing a server
Usernames resemble email addresses, such as a name followed by the server’s domain. Users can follow each other across connected servers with names in that format. Picking a server is therefore like picking an email provider: the choice matters, but it does not lock a person out of the wider network.
- Rules and moderation: read the server rules and see how reports are handled.
- Topic or region: many servers gather around a language, hobby or profession, which shapes the local timeline.
- Sign-up policy: some servers are open, others need approval or an invitation.
- Stability: volunteer-run servers can close, so check who runs it and how it is funded.
The documentation also covers moving or leaving accounts, so a first choice can be changed later.
Culture and moderation
Mastodon’s culture grows out of small communities. Rochko, the founder, believes that small, closely related communities deal with unwanted behavior more effectively than a large company’s small safety team. Server administrators can set their own rules and decide which other servers to engage with, so norms differ from place to place.
Posts are short-form status messages, historically known as “toots”. On a standard instance they can run to 500 text-based characters, more than Twitter’s 280-character limit, and some instances allow longer ones. Images, audio, video and polls can be attached.
Common habits include content warnings that hide sensitive text, alt text on images and hashtags for discovery. Only hashtags can appear in a Mastodon instance’s trending topics, not arbitrary popular words, which shapes how topics spread.
What the timelines show
A new user meets three main views. The home timeline shows posts from accounts the user follows, the local timeline shows public posts from the user’s own server, and the federated timeline shows public posts that the server has seen from the wider network. Because the home view is built from follows, the experience depends on whom a person chooses to follow rather than on a company deciding what to promote. That makes the first week a matter of curation: following a handful of active accounts and a few hashtags fills the feed faster than waiting for recommendations.
The same structure explains why the local timeline feels different on every server. A server for photographers will mostly show photography, while a general-interest server shows a mix. Newcomers often spend a little time reading a local timeline before committing, since it reveals the tone of a community more honestly than any rules page.
Etiquette that newcomers meet early
Habits vary by server, but a few appear almost everywhere. Content warnings fold away text on heavy or sensitive subjects so readers can choose whether to open it. Alt text describes images for people who use screen readers. Hashtags are written with capital letters for each word so that assistive software can read them clearly. Replies to strangers are generally expected to be polite, and moderators on many servers act quickly on harassment reports.
Moderation also works in layers. A user can mute or block an individual account. A server moderator can remove content, suspend a local account or limit how the server interacts with another server. Because each administrator sets policy, a server that tolerates abuse can find itself cut off by others, which acts as a social check even though no central authority exists.
Growth and development
The platform has seen several surges in adoption, most notably after Twitter’s acquisition by Elon Musk in 2022. Mastodon 4.0 arrived in November 2022 with post translation, editing and hashtag following. Mastodon 4.5 followed in November 2025 and introduced quote posts, which had previously been rejected. Mastodon is also interoperable with other ActivityPub platforms such as Threads, and many third-party apps work with it on desktop and mobile.
Growth brings trade-offs
Each surge of newcomers tests the model. Large waves strain volunteer-run servers, push moderators to review more reports and prompt new users to ask where to sign up. The design answer has been to spread people across many servers rather than concentrate them, which keeps any single operator from controlling the whole network. The cost is a steeper first step: a newcomer must choose a server before posting, which is a decision that centralized services never ask for.
Interoperability with services such as Threads shows the other side of the same design. Because the protocol is open, a larger platform can connect to Mastodon without asking permission, and Mastodon servers can decide for themselves whether to accept that traffic. Those decisions sit with each administrator and, indirectly, with the communities that choose to stay on or leave a server.
Getting started
- Pick a server and sign up, using the rules and focus as a guide.
- Set up a profile and write a short introduction with a few hashtags.
- Follow people and hashtags, including accounts on other servers.
- Learn the tools for dealing with unwanted content, such as muting and blocking.
- Try the official mobile apps or a third-party client.
A few practical tips help the first days go smoothly. Fill in the profile before following anyone, because many people check an account’s bio before following back. Introduce the account with a post tagged with a handful of interests. Look through the people followed by accounts worth reading, since follow lists are public and a quick route to relevant voices. Finally, remember that the account address includes the server name, so sharing the full handle lets friends on other servers find the account.
Anyone who prefers to run their own server can follow the documentation’s sections on preparing a machine and installing from source. Self-hosting gives full control over rules but adds maintenance work, so most newcomers start on an existing server and consider hosting later.
Since version 2.9.0, the web interface has offered a single-column mode for new users by default, while advanced mode approximates the TweetDeck-style layout.
Frequently asked questions
Who created Mastodon?
Eugen Rochko first released it in 2016.
Do both people need the same server to follow each other?
No. Servers federate through ActivityPub, so users can follow each other across connected servers.
How long can a post be?
A standard instance allows 500 characters, and some allow more.
Can a user change servers later?
Yes. The documentation includes guidance on moving or leaving accounts.
