A landcomm is a challenge community, that can be themed for a series, a genre (such as sci-fi, or tv shows only), or a type such as graphics or writing. You are sorted into a team and earn points for your team per challenge done. Team with he most points at the end of a round or phase wins. Phases generally run about 3-4 months.

They're called landcomms because the early ones were named like whedonland or Stargateland etc.