The clan system is central to Mirrors of the Wheel. Clans help define the character by providing an environment for role-play, as well as giving access to special skills and equipment. Characters have no specific class to label them, so their identity also comes, in large part, from the clan or clans to which they belong.
All characters in Mirrors are members of at least one clan and may be in two clans simultaneously. To begin with, characters will be members of a "newbie" clan and a homeland clan. Aiel and trolloc characters will have a tribe/clan rather than a homeland. It is possible to leave one clan and join another, so your character may be many things during her lifetime. For example, a woman may begin life as a simple peasant girl, then learn a craft and travel around the world as a member of a merchant guild until she meets some friends and settles down in a nation, joining the national army. Finally, she may grow weary of others and become a reclusive mystic, a bandit, or whatever else strikes her fancy.
Perhaps the most immediate benefit of joining a specific clan is gaining access to more skills and better teachers (see the Skills section). Most (in fact almost all) skills are taught by more than one clan, but no one clan teaches all (or even most) of the skills available in the game. Obviously, if you want your character to become a skilled master-at-arms, you are better off enlisting in an army than joining the local weaver's guild. Do not make the mistake of overlooking or underrating any clan, however. Each clan have different strengths and weaknesses and all will have at least one niche in which they truly excel. Perhaps that merchant isn't as skilled in combat as you are... He may have a troop of merchant's guards who are. Or maybe he holds the ear of certain local officials who can see to it that things happen...
As with everything in Mirrors, consistent role-play is expected of all characters. Nevertheless, different clans will have different standards that must be adhered to. Some clans will be rather loose in their requirements, enabling even the most casual player to have an enjoyable time. Other clans will not even entertain an application to join until you have demonstrated a role-playing history with your character in other clans.
Each clan can have up to twelve ranks. By advancing to higher ranks within the clan, you may become eligible to learn more closely guarded skills and secrets or have access to better equipment. Additionally, as you progress you may also be given more responsibilities and duties within the clan: sentry duty, stocking a store's inventory, delivering messages, etc... Faithful completion of assigned duties and tasks is necessary for continued advancement. Do not fear, however, as completing these duties will never require so much time that you are not spending most of you mudding experience doing whatever it is your character likes to do.
Eventually, you may become a clan master (Rank 7 for many clans). At this point you will become partly responsible for guiding and maintaining the clan. Clans in Mirrors are designed to be player run, with little to no immortal involvement. Setting entrance requirements, admitting new members, taking clan actions against other clans all are handled by the clan masters (If a clan does not have any masters, for example a new clan, or one whose characters have stopped playing, the rp imms may step in as a _temporary_ solution until the remaining members are ready to take over). Other, larger scale actions may involve the rp imm staff, especially if several clans are involved. For example, A feud between the Children of Light and the White Lions of Andor (both military clans) would not require any special staff involvement, as the players could handle everything involved. However, if the action escalated (perhaps by people observing and saying: wow, this is a great thing happening) and turned into a full scale war between nations, with mob troops and encampments sprouting up across the countryside, trade embargoes being enacted, etc... then the rp imms would work with the clan leaders to maintain and develop the scenario. Many players may simply not want the responsibility involved in the actual leading of a clan, so they may choose to stay at a lower rank, or move on to another clan. Some clans are very free-form and almost leaderless in this regard, with the other members simply voting on new applicants perhaps. Each clan is different, set up the way its members have decided it should be.