KGS Clans are a fun way to get together with a group of friends to play in a competitive way on KGS. Each clan has between 5 and 30 members, and plays a certain number of games per clan period, at the end of which it can participate in the Clan Brawl. See the Rules page for more complete information. There are a number of other tournaments which are often run throughout a clan period for clan members, too.
The idea is that you get together with your club/KGS room/forum/whatever and ask to create a clan, or if you just want to participate in the system, you find a clan willing to accept you and join that.
There is an official KGS Clans room, called "♦ The Battlefield". There's a diamond at the front of it's name, so it appears near the end of the room list in the Social category, above some rooms with Chinese names.
Creating a Clan
To create a clan, first ensure you have 5 members. Then you can post in the "Admin Stuff" forum, giving at least your clan's name, tag (4 letters or less) and the KGS user name of its leader. Once that's been dealt with, you'll have access to set your clan's roster and other information using your clan's admin page, and should add your other 4 members as soon as possible.
Joining a Clan
To join, look at the list of clans on the front page (particularly the recruitment info column) and pick one you'd like to join. Then send a message to the leader, either on KGS, or by signing up to the forum system (linked at the top of every page) and posting on that clan's forum. Hopefully the leader will accept you into their clan.
If you don't know which clan you want to join, Bucko's recommendation is to post on General Chat asking for a clan and join the clan whose leader replies first. :)
Once you've joined, you can start playing clan games immediately by saying your clan's tag at the start of any 19×19 games you play in The Battlefield.
