Hollywood in the Studio Era:
Explain what is meant by this term and name main studios 

The term 'studio system' was commonly used during a period of time known as the 'Golden Age of Hollywood'.It refers to a method of film production and distribution owned by a small number of 'major' studios in Hollywood although it is still commonly used today as a reference to the systems and output of the major studios. The term dates back to the practice of large motion picture studios between the 1920s and 1960s.
Five large companies, 20th Century Fox, RKO Pictures, Paramount Pictures, Warner Bros., and Metro-Goldwyn-Mayer came to be known as the Big Five trade publications and their management structures and practices collectively came to be known as the "studio system."

The ranking of the big five (in terms of the profit being made) was largely consistent during the Golden Age. MGM was number one for eleven years (1931-41), Paramount, the most successful sound studio within 1928-30 faded for the better part of the subsequent decade, and Fox was number two for most of MGM's reign. Paramount began a steady ascent in 1940, edging past MGM two years later and became the most financially successful of the Big Five (except for in 1932 when they lost money).

Hollywood became really successful during the Great Depression when films were used as a coping mechanism to help people escape their personal difficulties. President Franklin Delano Roosevelt said of Shirley Temple, "When the spirit of the people is lower than at any other time during this Depression, it is a splendid thing that for just fifteen cents an American can go to a movie and look at the smiling face of a baby and forget his troubles".