The Silent Age of Hollywood is one of the shorter ones, lasting less than twenty years, yet it would lay the foundation for everything that would follow.
It began in 1911, when a number of filmmakers from New York City, seething at the restrictions placed on the industry by Thomas Edison's Motion Picture Patents Company, moved west to California to escape the reach of his lawyers and set up the first film studio in Hollywood, a trolley suburb of Los Angeles that the fast-growing city had annexed a year ago. In 1924, to promote a new subdivision named Hollywoodland, a certain now-famous sign was erected (the "LAND" part was removed in 1949).
The Los Angeles area attracted filmmakers for several reasons: its perpetually warm and sunny climate allowing for constant film production with little regard to seasonal shifts in the weather, a relative abundance of cheap labor due to its proximity to Mexico, and a favorable court ruling from the 9th Circuit Court of Appeals (which covers the West Coast) that restricted Edison's ability to enforce patent law there. Another popular early destination, for many of the same reasons, was Hobe Sound, Florida, which was built up into the motion picture production center of "Picture City" during the Florida land boom in The Roaring '20s. However, the busting of the Florida real estate bubble in 1926, coupled with the 1928 Okeechobee hurricane, derailed these plans.
As early as 1915, the Los Angeles area had outpaced New York in terms of motion picture output, and by the end of the decade, the United States had claimed the title once held by France and Italy (whose film industries had been devastated by World War I) as the film capital of the world. During the Silent Era, seven of Hollywood's "Big Eight" studios emerged — Metro-Goldwyn-Mayer (the product of a 1924 merger of three companies), Paramount Pictures, First National Pictures (acquired by Warner Bros. in 1928), Fox Film Corporation (merged with Twentieth Century Pictures in 1935), Universal Pictures, Columbia Pictures, and United Artists. (The eighth, RKO Pictures, was a very minor studio in the silent era called Film Booking Offices of America.) It was also in this era that the "studio system" and the "star system" began to develop, forming the bedrock of Hollywood until the mid-20th century. More information on these systems can be found in the section on The Golden Age of Hollywood, which is when they reached their zenith.
In this era, film truly began to take off as a form of popular entertainment. The 1915 Epic Movie The Birth of a Nation pioneered a long list of filmmaking techniques and tropes, proved that cinema was commercially viable, and stirred a whole pot of controversy with its heavy-duty Unfortunate Implications. Unfortunately, there was also the case of Mutual Film Corporation v. Industrial Commission of Ohio in 1917 that had the US Supreme Court say that film as a medium was not a legitimate form of speech, but merely a product of a business, which made it open season for censorship for decades until the Supreme Court finally corrected this misjudgment in 1952 in the Miracle Decision.
In the 1920s, Hollywood reached a level of film output that has only been matched since then by Bollywood, with over eight hundred feature films being made per year. Initially, the studios tried to keep their actors anonymous to prevent them from becoming stars and demanding more money with their popularity, but ultimately proved impossible with a moviegoing public too curious to be denied knowing about the players. Notable stars of the silent era included Charlie Chaplin, Buster Keaton, Lillian Gish, John Gilbert, Clara Bow, Douglas Fairbanks, Gloria Swanson, Mary Pickford and child stars Jackie Coogan and Baby Peggy. The main competition that Hollywood had during this time came from vaudeville, a popular type of theater show consisting of acts by musicians, dancers, comedians, trained animals, magicians and acrobats. During this era, vaudeville had the chief advantage of having sound to back up what was going on on stage, which film didn't. But not for long...
The Silent Age of Hollywood is generally held to have lasted from 1911, with the opening of the first Hollywood studios, to 1927, with the release of The Jazz Singer, the first movie to include scenes with synchronized speech, and 1928, when Lights of New York, the first full-length 100% "talkie", came out. See Rise of the Talkies for what happened then.
The Library of Congress estimates that 75% of silent films produced in the United States have been lost. The Film Foundation (Marty Scorsese's outfit) asserts that 90% of the released films from this period have been lost, mostly to a few spectacular fires in studio film vaults.
For what was going on in animation of the time, see The Silent Age of Animation.