Convergence theory argues that collective behavior is not merely a result of the crowd's influence, but rather the result of like-minded individuals coming together. It suggests that people with similar motivations, values, or frustrations are drawn to the same events. Therefore, the behavior of the crowd is a reflection of the pre-existing characteristics of the people who chose to participate in it.

In sociology, a 'mass' refers to a large number of people who are relatively anonymous and heterogeneous, often sharing a common interest or focus. While 'public' refers to a group discussing issues, 'mass' emphasizes the scale and the nature of the collective behavior often associated with modern industrial societies.

Collective behavior refers to spontaneous, unstructured, and often transitory social actions. Sociologists categorize these into distinct forms, including crowds (temporary gatherings), the mass (dispersed individuals reacting to similar stimuli), the public (groups debating issues), and social movements (organized efforts to promote or resist change). These forms represent the diverse ways individuals act collectively outside of established institutional norms.

Social control refers to the various mechanisms, strategies, and institutions that society uses to maintain order and regulate behavior. In the context of collective behavior, social control acts as a counter-force that can limit, redirect, or terminate the actions of a crowd or social movement, thereby restoring stability to the social system.

While traditional terrorism was often focused on specific local or national territorial disputes, contemporary or 'new-style' terrorism is characterized by global networks, transnational reach, and ideological goals that transcend national borders. This shift in scale and ambition is a defining feature of modern terrorist organizations.

A collectivity is a large number of people whose interaction is less structured than that of a formal group. Unlike primary or secondary groups, collectivities operate under loosely defined norms and lack the stable, long-term social organization found in institutionalized social groups.

Nonviolent protest strategies are methods used by social movements to express dissent or demand change without resorting to physical force. Rallies, marches, and petitions are all classic examples of peaceful collective action designed to mobilize public opinion, demonstrate the strength of a cause, and pressure authorities to address specific grievances.

In sociology, collective behavior refers to spontaneous, unstructured actions by large groups. Both 'masses' and 'publics' are classic examples of such collective groupings. A mass consists of people who are geographically dispersed but share a common interest, while a public is a group of people who discuss issues of common concern. Governments, by contrast, are formal institutions rather than spontaneous collective groups.

The term 'terrorism' originated during the French Revolution, specifically during the 'Reign of Terror' (1793–1794). It was initially used to describe the actions taken by the revolutionary government to maintain control and suppress perceived enemies of the state through systematic violence and intimidation.

In sociology, fashions are defined by their broader, more sustained acceptance across a significant portion of society, reflecting cultural trends. In contrast, fads are characterized by intense but short-lived enthusiasm, typically limited to specific subcultures or segments of the population, lacking the longevity and widespread integration of fashion.