Film, also called movie or motion picture, is a visual art-form used to simulate experiences that communicate ideas, stories, perceptions, feelings, beauty or atmosphere, by the means of recorded or programmed moving images, along with sound (and more rarely) other sensory simulations. The word cinema, short for cinematography, is often used to refer to filmmaker and the film industry, and to the art form that is the result of it.
(Wikipedia)

You can find out a lot more about movies in Wikipedia and internet.
But I like to say my opinion about Films or movies.
Every movie has got messages. The thing we should care about movies apart from the enjoy and filling leisure time is finding out the message. Every movie reflects the opinion of the movie makers (writers, directors,...)
The movies can teach us a lot. We may think we know our society a lot but that is not all. There are many hidden aspects that we dont know or ignore in the society, Very important aspects.
So I suggest we watch movies more carefully and find out the messages. These messages can be political, scientific, social, international, etc....