Mastodon, the Social Network(s)
Mastodon is sorta twitter a distributed microblogging platform. Instead of a single server that everyone uses, there are many, many servers and no restrictions on setting them up. If you just want to get to microblogging and talk to other people who are using Mastodon, my short answer for you is: go sign up at mastodon.social. That's it! That's all you need to do to get started!
Oh, some of you are still here! So, you might choose a different Mastodon server if you are looking to meet people who share your server. Mastodon.social has all kind of people, so looking at the "local" timeline (just the people who are also on mastodon.social) is going to find you a whole lot of different people who are there for different reasons. Maybe you want to find people to talk about computers with and cybre.space feels more like your kind of people. Or something like wandering.shop, a server started by science fiction and fantasy fandom and writers - they welcome anyone and are going for a specific coffee shop chat kind of vibe.
joinmastodon.org has a search function to help you find a server that fits you:
I couldn't get the full list into the screenshot, but I know some of you want to choose "in academia" for instance! (There exists a scholar.social and I am following at least one person there)
What I did was start at mastodon.social and see who I was following the most and finding most interesting in the "global" timeline (every other server your server chooses to federate with - probably not all of them) and then get an account on a place that felt like "my kind of people"
Currently, I can be found on mastodon as @ansate@weirder.earth