You have probably seen this and maybe are or are not in the osu!dev Discord server. If you are, then you know there are osu! development work going on in there. What you probably don't know is that there are also other things going on in there. This thread details the Discord server so you know what it is and what goes on in each of the channels.

When you first join the server you will be in the #arrival channel with no write access to any other channels. Read the info in the #welcome channel to know how to gain write access to all other channels.

DEV

#osu-lazer - osu!lazer is osu! rewritten from ground up and will eventually replace the current client with a new updated look and features. All coding related things related to osu!lazer happens here. New osu!lazer releases are posted every so often here. Keep in mind it's still in development and not perfect.

#osu-framework - osu!framework is the engine osu!lazer runs on. You can make your own gamemodes using it or even your own games! All coding related things related to the osu!framework happen here. If you got questions on how to use it, you can also ask here assuming you have decent knowledge of C# already.

#osu-web - All coding related things related to the osu! website happens here. If you do find an issue with the website or have a suggestion you can post it here.

DIFFICULTY

I am going to group together all four channels since they are pretty much for same thing. Stuff related to pp and star rating (sr) development happens in these channels. This is more technically oriented development, so suggestions or ideas on how to fix pp or sr are better suited for the feature requests subforum instead. These channels are more for stuff related to algorithms, mathematics, formulation, statistics, etc rather than random ideas.

COMMUNITY

#osu-spotlights - Each season or so maps are picked out as a group for their own leaderboards and ranking. You might have even gotten a spotlight medal once! You can check out the spotlights here. Suggestions on how to make spotlights better can go in this channel.

#osu-wiki - Management of osu!wiki happens here. You can contribute to the wiki yourself if you'd like! Make sure to check out the osu!wiki contribution guide if you think you want to.

#osu-loved - Management of loved beatmaps occurs here. As of writing this the channel is mostly inactive since most of that management work occurs in other discord servers.

MAPPING

#modding - Modding management occurs here. Here you would find BN and NAT meetings and other administrative discussions. Summary of those discussions are occasionally posted in the Mapping Management subforum. Proposals for ranking criteria are better suited for the ranking criteria subforum instead. Modding help is better suited for the Mapping Discussion subforum instead. Modding requests is better suited for the Modding Queues subforum instead. Map requests belong nowhere.

#mappers-guild - Mapper's Guild are a group of talented mappers who create maps by featured artists for various rewards. You can find more information about Mapper's Guild here. All discussion relating to that happens here.