At TarValon.net, the organization was modeled after the Wheel of Time series by Robert Jordan. As such, from the beginning women were able to choose one of seven different Ajahs to join based on their interests and personality. As time went on, it was decided that men deserved the same opportunity to choose a fellowship of brothers, so three Companies were created initially with a fourth to join them a few years later. Each of these Community Groups has a headquarters through which more can be learned about them so please explore at your leisure!
As in the books, there are seven Ajahs, the initial philosophy of each being modelled on the Ajah in question. However, as we are in the real world, much of what is applicable in the books is not applicable here so the Ajahs have developed over time, each of them having their own distinct feel, sometimes very similar to that of the books, other times less so.
With a large male population, the need was felt to create groups akin to the Ajahs to which the men could belong. There were intially three set up, based on broad personalty traits, with a fourth joining them some years later