The Memoirs of a Woman of Pleasure, more commonly known as Fanny Hill, is first known English prose pornography. It tells the adventures of one Fanny Hill as she loses her virginity at 15, meanders in and out of prostitution, falls in love but loses her man, masturbates, has lots of sex with both men and women, watches two men having sex (this part was apparently added later), and eventually finds her true love again, who proposes marriage as the book ends.
The author, John Cleland, wrote the book while in debtor’s prison in 1748. It has been banned many times over the years in many places, and it wasn’t until 1973 that the book was finally published without threat of ban in the U.S. It first became a film nine years earlier however, in 1964 – it’s been remade a number of times since then, including a 1983 version with Oliver Reed, Wilfred Hyde-White and Shelley Winters.
The text of Fanny Hill can be found its entirety at Project Gutenberg, here. The 1964 film has a page on IMDB, here, as does the 1983 film, here, and the most recent BBC production in 2007, here (you can watch an excerpt at Youtube here). The book also has a page on Wikipedia, here.