Demographics and psychographics

Demographics:
Category A - upper middle class (bankers, doctors)
Category B - middle class (teachers, middle managers)
Category C1 - lower middle class (office supervisors, nurses)
Category C2 - skilled working class (tradespeople)
Category D - working class (unskilled manual labour)
Category E - lowest level of income (unemployed, students, pensioners)

Psychographics:
Adverts are more likely to be identified using psychographics rather than demographics, however you can apply them to other media products as well.
Aspirers - people who want to appear rich and attractive.
Reformers - people who want social change, unemployed by status, make decisions based on their values (environmentalists).
Explorers - adventurous people who like taking risks.
Main-streamers - people who follow the crowd.
Strugglers - people who find it hard to achieve (often connected with poverty). 

Ideology (shared values and beliefs). Also consider audiences' values (e.g. concern for the environment) and ideologies (e.g. predominant left or right wing stance, a distrust of the youth or sexism), which they may share with the text.