A term from 1857 meaning the ‘description of prostitutes,’ from the French pornographie, from the Greek pornographos meaning ‘(one) writing of prostitutes’.

An image from circa 1890 of a contemporary prostitute
From porne ‘prostitute,’ originally meaning ‘bought, purchased’ with an original notion of ‘female slave sold for prostitution’.
It is related to pernanai ‘to sell,’ from the -pie root. The per- ‘to traffic in, to sell’ is related to the Latin pretium meaning ‘price,’ plus graphein ‘to write’.
Originally used of classical art and writing; application to modern examples began 1880s. Main modern meaning ‘salacious writing or pictures’ represents a slight shift from the etymology, though classical depictions of prostitution usually had this quality.
Pornographer is earliest form of the word, attested from 1850. Pornocracy from 1860 is ‘the dominating influence of harlots,’ used specifically of the government of Rome and the papacy during the first half of the 10th century by Theodora and her daughters.