Social Movements

Social movements are any broad social alliances of people who are connected through their shared interest in blocking or affecting social change. Social movements do not have to be formally organized. Multiple alliances may work separately for common causes and still be considered a social movement.
A social movement organization is a formally organized component of a social movement. But an SMO may only make up a part of a particular social movement.
Modern social movements became possible through the wider dissemination of literature and increased mobility of labor due to the industrialization of societies. 

Types of social movements are

Social movements theories

1.deprivation theory

Deprivation Theory argues that social movements have their foundations among people who feel deprived of some good(s) or resource(s). According to this approach, individuals who are lacking some good, service, or comfort are more likely to organize a social movement to improve (or defend) their conditions.

2. mass society theory

Mass-Society Theory argues that social movements are made up of individuals in large societies who feel insignificant or socially detached. Social movements, according to this theory, provide a sense of empowerment and belonging that the movement members would otherwise not have.

I think social movements are caused by people's desire for better living. According to the social movements theories, it happen with who want more comfortable and enjoy prosperity high quality life.So social movement is natural phenomenon.