What is Mastodon?

Mastodon is a social network similar to Twitter, but it is free and open-source for administrators to run their own communities, called "instances", centered around a particular topic or theme. It allows users to create short messages, called "toots" or "posts" (depending on your instance), and share them with others. Users can also follow and interact with other users either on their "local" instance or on other instances.

Mastodon was created by Eugen Rochko and the initial release was in March 2016. The software is now maintained by the German non-profit, Mastodon gGmbH.

Decentralization

All of the instances communicate together, but there is no central service that coordinates all of the servers like many other social networks. It is referred to as a decentralized network not owned or controlled by a single company or organization -- instead it is made up of instances that are run by... anyone! All nodes are independent with their own codes of conduct, terms of service, and other policies.

Features

Mastodon has a number of features that are similar to those found on other social networks, such as the ability to post updates, share links, photos, and videos, and interact with other users through favourites, comments, and boosts. It also has a number of unique features, such as the ability to create custom emoji and have more granular privacy controls on individual posts.

Benefits

One of the main benefits of Mastodon is that it is a federation of instances. If one instance gets shut down the others will all continue to work together. If there is a bad actor on the network it can get "defederated". This also allows for greater control over data privacy and gives users the ability to choose which instance they want to join based on its policies and community.

Another benefit (or drawback depending on your outlook) is that Mastodon can feel like early 2000-era web services. The community can be earnest and believes in the social good of free and open source software. Because the benefits

Lack of ads and the incentives of a for-profit company to monetize engagement.

Drawbacks

For a normal user of Twitter or other microblogging social networks, Mastodon will feel very similar. The main drawback is that there are less people on the network, especially celebrities, athletes, and politicians. If you don't care about seeing that content in your feeds (like me!) then this isn't such a bad thing.

Because Mastodon is a federation of instances, the first hurdle for most users is choosing an instance. The nice thing is that this isn't a binding choice and you can transfer from any instance you choose to another whenever you want. joinmastodon.org has a list of servers that can be filtered by region or topic. If you are consumed by analysis paralysis, you can always join mastodon.social which is the canonical Mastodon instance.

Mastodon is also relatively new (compared to other social networks), so there are less tools and ecosystem built around it. However, that seems to be changing over the past few months with more attention drawn to Mastodon after Twitter was bought by Elon Musk. Here is a continually updated list of tools for Mastodon.