Although people occupy a bunch of
status positions, the
master status is usually the one that most
defines them and
overshadows all the others. At least in
Western culture,
gender,
race, and
occupation seem to be the most
common.
One of the most important things about a person's master status is that it is not usually chosen. The gender and race statuses are pretty obvious but when you get into the occupational status things get more muddy. This is becoming more common as less people actually decide what they will do for a living. With an undergraduate degree offering about the same amount of prestige as a business card these days, occupation is on the rise as an ascribed status.
The master status also defines or at least influences all other aspects of a person's life. The inevitable conflicts between statuses can force people to split themselves (much like W.E.B Debois' concept of the double identity) into stereotyped roles to minimize the conflict and the social pressure that can come with it. Usually the master status wins out whether the person is conscious of the exchange or not.
Because the master status is basically a social avatar it also influences all kinds of social interactions. I think of it as akin to putting words into someone's mouth.