 Character analysis includes identifying characters of the organisms we are looking at, and in particular, identifying when a character in one organism is the same character as in another organism. This is the problem of homology. A different, but related problem, is assigning character states. For example, one bear might have black fur while another has white fur. Here, “fur” is the character, but it is in a different state (fur color) in the two organisms. Though it is standard to treat characters and character states separately, the extent to which these are genuinely different problems rather than than aspects of the same problem is a matter of debate (Stevens 2000; Freudenstein 2005; Sereno 2005).