The goal of this wiki page is to share information on distributed, and decentralized social media platforms. It's recommended to read w/basic_security and w/privacy before engaging with any kind of social media. The page can be expanded in many ways: If someone wants to breakdown privacy on the Fediverse and doing personal content moderation that would be very helpful.
The thing that draws most people into social media is the ability to connect with people around the world. To be able to compete with the major social media in many different ways (accessibility, moderation, responsiveness to name a few) these platforms utilize a common open standard to intercommunicate. Activitypub is an example of this open standard. Using a standard language means that regardless of which platform/instance you choose as your home base you will be able to see and connect with any other user or instance as long as they have not blocked you or your instance. You can explore a map of the Fediverse here
Here is a list of some platforms and their use cases. I would recommend reading more about these and various other platforms at https://fediverse.party/.
Mastodon - One of the largest Fediverse members. If you are looking for a familiar social media experience but with all the advantages of being libre, and decentralized or you are just getting started this is a great choice.
Diaspora - Diaspora blends blogging and social media in an interesting way. It can be compared to Fedbook with many improvements.
Plemora - A very lightweight program with a large user base. It is cross compatible with most Mastodon clients and has a couple cool improvements on Mastodon.
You've found a platform that looks good to you so which instance do we choose? Don't let this part of the process overwhelm you. You're not stuck on an instance forever, and you can be on multiple instances at once. The only things to look out for is wether or not they block bad instances and moderate bigotry and other crappy behavior. Here is a list of Mastodon instances that do those things. Pick one with topics you like and/or domain you think is cool and dive in!
There is also an instance hosted by a Raddle user at https://ni.hil.ist.