This is certified as the 100th article on the Kingdoms of Camelot Wiki!
A player is, unsurprisingly, a human who participates in Kingdoms of Camelot.
Any individual member of Facebook or MySpace can become a player, either from a link on the Game's application page or from a link posted by a friend. Players can choose between playing on a single domain or on several at once. Initially a player is placed in a random domain unless responding to an invitation from a friend to join him or her.
Even though it is not literally possible, every player is plotting takeover of your castle - you must preempt this and strike first!