 So in this session, we are going to discuss collective behavior, how we can define collective behavior, how it is different from individual behavior, and what are the major types and categories of collective behavior. So when we want to highlight that what is collective behavior, that is basically the kinds of activities engaged in by sizable but loosely organized groups of people. That is, collective behavior is not necessary, that for a specific purpose, people will be together, so we will call it collective behavior, where the groups of people are together, they are involved in some activities, which are matching in one way, so we can call it collective behavior. So the episodes of collective behavior tend to be quite spontaneous, that is, people are together, there has been an incident, there has been an accident, of course, now everyone will react in the same way, resulting from an experience shared by the members. If the members are there, their behavior is in one way, they react in the same way, so that is collective behavior. And there are mainly three forms of collective behavior, number one, the crowd, number two the mass, number three the public, but the crowd, that is basically the type of behavior which can be further categorized into some categories, like the casual crowd. The casual crowd, that is a collection of people who happen to be in the same place at the same time. The people in this type of crowd have no real common bond, long term purpose or identity. But the casual crowd, it is the same as when people gather in a city, in a city, but they do not have any special purpose to gather, there is no theme, there is no organized form of gathering, they do not have any specific purpose, they have no identity. Conventional crowds, a conventional crowd is a collection of people who gather for a specific purpose. But now these people, when they have a special purpose, then we will call them conventional crowd. Then there is a category of expressive crowd, expressive crowd and expressive crowd is a collection of people who gather primarily to be excited and to express one or more emotions. Now people are gathered to watch cricket match, to watch football match, to listen to speech match. This is what is called protest crowd. Now protest crowds are the people, who are gather together in a specific purpose, or by something to protest, that is to say their planning or purpose. Another thing that we have to understand is, what is called a mass in the collective behaviour. The gathering of people having no particular aim or objective. The gathering of people having no particular aim or objective. For example, when we see a group of people in the market, who have no purpose or aim, but when we see a group of people, we can see the movement of the group. Then another category is the public. Who is the public? The public who has a specific theme will be concerned about a specific issue. And to express that, to show their feelings, they are called public. Another common form of collective behaviour is the social movement. The study of social movements exploded in the 1960s and 1970s, specifically in US, when people initiated and started social movements with a specific purpose or objective. So, we have discussed the nature of collective behaviour and the theme and types of collective behaviour.