1. Erotica refers to depictions of sexual nature. These depictions are generally artistic in nature. True, it deals with stimulating or sexually arousing subject matter, including painting, sculpture, photography, drama film, music or literature. If an artistic painting can elicit feelings of arousal, that's good! We're sexual beings.
2. However, one needs to ask the difficult question: Is the erotica of 16-18th centuries an equivalent of our pornography today? If a young person reads Bocaccio's 14th century Decameron would he/she feel sexually aroused? Yes. And yet, Bocaccio is doing literature. And to complicate matters a bit, Decameron was censored.
The first instance occurred when the Dominican Friar Girolamo Savonarola incited a bonfire of 'sinful' art and literature in the centre of Florence known later as the "Bonfire of the Vanities" (February 7, 1479). The Decameron was among the works known to have been burned that day.
3. Erotica harks back to prehistoric times, as seen in the venus figurines and rock art. glyptic art from the Sumerians, votive plaques from Mesopotamia, Assyrian lead votive figurines, China, India, etc.
4. The excavations of Pompeii were undertaken in the 1860s, and revealed much of the erotic art of the Romans. erotic postcards were a luxury during the monarchy in Europe. and many artists worked as erotic artists for x-tra income.
check this excellent display of Carracci's erotic illustrations @ Wikipedia
plus other erotic engravings,