Pigeonholing is a process that attempts to classify disparate entities into a limited number of categories (usually, mutually exclusive ones).

The term usually carries connotations of criticism, implying that the classification scheme referred to inadequately reflects the entities being sorted, or that it is based on stereotypes.

Various classification schemes often suffer from pitfalls such as these:

An example of pigeonholing in everyday conversation occurs when a person making an apolitical or barely political comment is assumed to have a certain political belief, without ascertaining their political stance. Such an erroneous designation is especially erroneous when assigning it to people who live in places where the left–right dichotomy is not present.