Movies - one of the common industry across all of the nations in the world, yet very different in the content of it. The reason for existence of movie industry is very simple - Humans love stories. Yes, we do. When we are young, we had mom and people around to tell stories. Beyond a point, we have movies. This I believe is the single most important reason for the success of this industry.
This is an industry that spawned out of our need for imagination - coz stories are imaginative. Some are factual, some are reflective, some are imaginative. In a way, all the things we do in life comes out of imagination and movies offer us to experience it - visual medium.
I dont know the exact history, well, not much of it at all - but dont know how and where this medium came to existence. It can be traced to drama or puppet show or what not. However, from what I know, they have been a powerful medium, coz they involve people. For the people, by the people, to the people (again, come to think of it, everything is for/by/to the people in the world - where am I going ? ) Movies have been used to pass down messages to the people, for instance in Indian freedom struggle, movies played a role. Even now in life, some movies send across inspirations messages/feel/vibe to the point of being the inception of something ;).
And - movies are also separated out for their content off late. Some of them are called realistic, some documentary, some entertaining, time pass and what not. For eg: A movie like slumdog millionaire may be entertaining, inspiring and treat to watch for many people all over the world. However, it may not be the same way for the guys who live the life of the roles played in that movie. For eg: a guide in Taj Mahal or the waiter person in the hotel. For them, the slumdog movie may not be their cup of tea as they dont want to see what they go through everyday also illustrated in screen with more music and dramatization.
Preferences, separation of movie in to different genre and other things also reflect something else about ourselves as well. The difference that is in all of us - reflects in different genres and preferences and choices. All these difference come in to existence coz we ain't struggling for basic amenities anymore (well we are at one higher level, but not at individual level in most countries barring few). For instance in a poverty stricken country, eg a country in African continent or war torn country in middle east - the choices and preferences may not exist for the movies - coz they are happy with whatever is available as the priorities are elsewhere. An individual can have the liberty of having the option of having options or choices - when his/her needs are met or basic necessary thing for each of the individual is taken care of.
Same logic applies for movie genre or what people enjoy - if the society at large is stressed out or living in a dire straits, a documentary movie may not appeal as their life itself is may currently be documentary types. Movies also reflect the same - the taste preferences of what an audience can afford to accomodate.
Well, all said and done - its still our stories, our figment of imagination and we choose what we want to imagine in the larger screen and be told ;-)