Neil smelser's theory of crowd behavior is referred to as theory:

Neil Smelser suggested a theory of structural strain that links existing social conditions to the emergence of collective behavior. crowd a temporary grouping of individuals who are physically close enough to engage in social interaction mob a special type of crowd that is wildly out of control and is intent on doing violence and harm casual crowd a type of crowd that consists of people who are passive and have a low emotional engagement and little social interaction with those nearby