The period from 1920 to 1929 brought the culture of "stars" such as Garbo and Keaton, and the growth of the movie moguls. Those moguls introduced production companies such as Warner Brothers, MGM, 20th Century Fox and Paramount. The films tended to be westerns, epics and comedies and, to show them, extravagant picture palaces started to open up.
In 1927 there was a giant leap forward when sound was introduced and this led the industry into the 1930s when the cinema could be said to have come of age, with a new generation of actors who could talk on screen and the concept of the double bill. Technicolour followed in 1935 whilst the film "Snow White and the Seven dwarves" was the first full length animation film. However, whilst these innovations were taking place, the Great Depression affected demand and a number of the studios merged to reduce costs.
The War in Europe that spread to the world in 1941 brought a change in emphasis with propaganda films and darker movies reflecting the times such as Casablanca and Citizen Kane. Audiences grew again but the studios started to lose their iron grip and Post war there were further innovations such as drive in movies, 3D, Cinerama and Cinemascope as the industry launched a comeback against TV.
Despite this there was a decline in audiences from the 1960s. The response in the 1970s was a new breed of directors and more violent and horror films such as Jaws. It also saw the first of the Star Wars films and the growth of spin off merchandising and the introduction of videos.