Discrimination is the act of making unjustified distinctions between human beings based on the groups, classes, or other categories to which they are perceived to belong. People may be discriminated on the basis of race, gender, age, religion, or sexual orientation, as well as other categories. Discrimination especially occurs when individuals or groups are unfairly treated in a way which is worse than other people are treated, on the basis of their actual or perceived membership in certain groups or social categories. It involves restricting members of one group from opportunities or privileges that are available to members of another group.