Routine activity theory, like the related lifestyle-exposure theory, emerged as a key theoretical approach in criminology in the late 1970s. Routine activities refer to generalized patterns of social activities in a society (i.e., spatial and temporal patterns in family, work, and leisure activities). A key idea is that the structure of routine activities in a society influences what kinds of situations emerge, and changes in a society`s routine activities cause changes in the kind of situations people confront. Another key idea is that people act in response to situations (including when they commit crimes); therefore, the kinds of situations they encounter in their daily lives influence their crime involvement (and, as a result, influence a society`s crime rate), and changes in people`s exposure to situations may lead to changes in their crime involvement (and consequently, changes in a society`s crime rate).