Flatpaks: NOT Ubuntu's containerized deliverable. They use snaps. Flatpaks are more Fedora's thing. I know Mint uses flatpaks, and Silver blue relies heavily on them. Snaps v Flatpaks are like Coke v Pepsi. It's all just sugar water, but people care, for reasons.
Tailscale is a tunneling service which allows to easily connect multiple different networks together. For example, if you have two computers in different locations, they can talk to each other as if they were in the same location using a tailscale network.
Well these are all nerd terms, because most of the community in here consists of IT guys and people who use Linux, most of the time they are the same. You don't need to know what Docker, Self host, Fork, Container, Flatpak, Tailscale, Distro, Wayland and Nginx is, unless you are interested in IT.
Knowing Federated and Instance could be beneficial for the Lemmy users I think.
Federated: Imagine you are the resident of town X, and you frequently communicate and engage in town X, but you can also communicate with your best friend who lives in town Y, and your parents who reside in town Z. This is how Lemmy and Mastodon works instead of social media like Reddit, FB, Insta etc etc, where with my analogue the residents live in 1 capital city with no towns to talk with, and having to abide by their rules, whereas different towns may have different laws.
Instance: Following my analogue an instance is a town of this federated world. For example you are the resident of sh.itjust.works town and I'm living in sopuli.xyz
I think the only "required" one on your list is Instance: It's one out of many servers. Lemmy.world, sh.itjust.works, etc.
I find it useful to think of it topologically like an IRC server, if you're familiar with how those work; many of them connect and share content - You're on an instance/server, but can interact with users and content from different ones.
The rest are more oriented towards Linux, servers (in general), and aren't really required for Lemmy use in general.
This is where I started to explain what a codebase fork is, but then I realized that I fucking hate typing on my phone.
Tailscale: a VPN -esque service that lets you connect networks together in fun and interesting ways. For instance: I can use tailscale to access my home network from my phone!
An instance is a specific computer a person uses .
Let's say lem.ee is still up and you login there and have an account there but we both browse the rpgmemes on .ttrpg
Lem.ee is an instance, lemmy.world is an instance the .ttrpg computer is an instance. Like different email servers , these computers all talk with each other to make it seamless. All of the computers use the Lemmy software.
Now lem.ee has shut down, users can't login there , but a new Lemmy instance could be created by someone and connect to the federated network.
But a university might run it's own instance of Lemmy, giving students an account and have their own communities which aren't publicly shared and they aren't federated.
People can say there's an issue with federation where people may leave comments on another computers community but they're not visible to users browsing others. E.g. users on lemmy.workd might see it and .ttrpg but not anywhere else. They are meant to but an issue like slow communication is preventing it not permissions as such.
A fork is a different version of software. Open source software licences allw people to modify and re release the programs.
two developers might have different visions of what a software should look like , and if they want to split and make their own versions, that would be a fork in the development of the program.