An erotic wall painting from Pompeii
Pornography has an extensive history. Sexually suggestive and explicit artwork is as ancient as artwork of any other content; explicit photographs date to very shortly after the invention of photography; and among the earliest films are works depicting nudity and explicit sex.
Nude human beings and sexual activities are depicted in some paleolithic art (e.g. Venus Figurines); however, it is not certain that the purpose was sexual arousal, as the images may have had instead a spiritual significance. There are numerous pornographic paintings on the walls of ruined Roman buildings in Pompeii. One notable example is a brothel in which the various sexual services are advertised in murals above each door. In Pompeii you can also see phalli and testicles engraved in the sidewalks, pointing the way to the prostitution and entertainment district, to aid visitors in finding their way (see Erotic art in Pompeii). Archaeologists in Germany reported in April 2005 that they had found what they believe is a 7,200-year-old pornographic scene depicting a male figurine bending over a female figurine in a manner suggestive of sexual intercourse. The male figure has been named Adonis von Zschernitz. 
Pornographic comic books known as Tijuana bibles began appearing in the U.S. in the 1920s.
In the second half of the 20th century, pornography in the United States evolved from the so-called "men's magazines" such as Playboy and Modern Man of the 1950s. These magazines featured nude or semi-nude women, sometimes apparently engaging in the act of masturbation, although their genitals or pubic hair were not actually displayed. By the late 1960s, however, these magazines, which by then included Penthouse, began to evolve into more explicit displays, eventually, by the 1990s, featuring sexual penetration, lesbianism and homosexuality, group sex, masturbation, and fetishes.
The first explicitly pornographic film with a plot that received a general theatrical release in the U.S. is generally considered to be Mona (also known as Mona the Virgin Nymph), a 59-minute 1970 feature by Bill Osco and Howard Ziehm, who went on to create the relatively high-budget hardcore/softcore (depending on the release) cult film Flesh Gordon.
The 1971 film The Boys in the Sand represented a number of pornographic "firsts." It was the first generally available gay pornographic movie. It was the first porn film to include onscreen credits for its cast and crew (albeit largely under pseudonyms). It was the first porn film to parody the title of a mainstream movie (in this case, The Boys in the Band). And it is the only X-rated pornographic film to be reviewed by The New York Times.
Technology and pornography
Mass-distributed pornography is as old as the printing press. Almost as soon as photography was invented, it was being used to produce pornographic photographs. Indeed some claim that pornography has been a driving force in the take up of technologies from the printing press, through photography (still and motion) to video, satellite TV and the internet
With the arrival of the Internet, the availability of pornography increased greatly. Some of the most successful internet entrepreneurs are those who operate pornographic internet sites. As well as conventional photographic or video pornography, some sites offer an "interactive" video game-like entertainment. Due to the international character of the Internet, it provides an easy means whereby consumers, residing in countries where pornography is either entirely illegal, or at least that which does not furnish physical proof of age, can easily acquire such material from sources in another country where it is legal or remains unprosecuted. See internet pornography.
The low cost of copying and delivering digital data boosted the formation of private circles of people swapping pornography. With the advent of peer-to-peer file sharing applications such as Kazaa, pornography swapping has reached new heights. Free pornography became available en masse from other users and is no longer restricted to private groups. Large amounts of free pornography on the Internet is also distributed for marketing purposes to encourage subscriptions to paid content.
Since the late 90's, "porn from the masses for the masses" seems to have become another new trend. Cheap digital cameras, increasingly powerful and user-friendly software, and easy access to pornographic source material have made it possible for individuals to produce and share home-made or home-altered porn for next to no cost.
On the Internet, pornography is sometimes referred to as pr0n which is misspelled p0rn — porn written with zero, a common style in a so called leet speak. One theory on the origins of this spelling is that it was devised to fool text filters on instant messaging programs or chat rooms.
According to Google, 68 million searches including some variation of the word "porn" occur every day.