Pornographic films are motion pictures that explicitly depict sexual intercourse and other sexual acts, typically for the purpose of sexual arousal in the viewer. They appeared shortly after the creation of the motion picture in the early 1900s. Pornographic films have much in common with other forms of pornography. Pornography is often referred to as "porn" and a pornographic work as a "porno." Older names for a pornographic movie include "adult film," "stag film," and "blue movie." In general, "softcore" refers to pornography that does not depict penetration or "extreme fetish" acts, while "hardcore" refers to pornography that depicts penetration and/or extreme fetish acts.
Throughout its history, the movie camera has been used for pornography, but for most of that time pornographic movies were typically available only by underground distribution, for projection at home or in private clubs. Only in the 1970s were pornographic films semi-legitimized; by the 1980s, pornography on home video achieved distribution unimagined only decades earlier. The rise of the internet in the late 1990s and early 2000s similarly changed distribution of pornography, and furthermore complicated legal prosecution of obscenity.