Anyone can create their own Mastodon server, however this can be challenging technically and expensive depending on how large the server is. With that, there are lots of existing Mastodon servers! And you have to choose one to sign up.
Servers are created for a lot of reasons, but generally they are homes for an interest area, geographic region, or security concern. Some are large with 100,000s of users and some only have 1 user. Unless you have a special interest area, you should probably join a general purpose server like https://mas.to. Each server has it's own rules, moderation procedures, and list of which servers they connect to and which they don't.
While it seems like a big commitment choosing an server, you can change servers at any time after you join Mastodon. Don't sweat it, your data is portable on Mastodon.
2. Read and accept the server rules
Every server has its own intended audience, safety procedures, and content restrictions. When joining a Mastodon server, you are made aware of the rules and have to confirm you will abide by them. Every server sets up its own guidelines, so some are very lenient and others are very explicit. There are even servers you have to apply to join. These rules are in place to maintain the community and keep everyone safe.
3. Create username and password
4. Confirm account
After to input your new account details, you'll be instructed to check your email and click the confirmation link sent to you. CONGRATS! You are now on Mastodon and ready to post, follow, and view. 🎉
5. Set up privacy options for your account
By default, anyone can see your posts and follow you. Consult the following page for details on how to change the visibility of your posts and privacy of your account.
6. Optional: select an app to interact with Mastodon
One of the cool things about the fediverse is that even though you are using a specific system like Mastodon, you can view the system however you like. Instead of having to configure this yourself, there device apps and use a web apps that help streamline your browsing and posting.
Following is a short list of options (note some of these apps must be purchased). Your choice really is a personal preference.
