The word is often used to describe photographers who specialize in photos of celebrities. The word has become tag for this people who follow celebrities to take annoying pictures of them. The word came to be in Frederico Fellini’s 1960 film La Dolce Vita, the word was taken from that movie and became synonymous with pesky photographers in 1968. There was a character in the movie named Signor Paparazzo(singular form of paparazzi) he was obnoxious, creepy and stalker, he was hated by the celebrities.
Before the modern meaning the Italian word meant a buzzing insect which isn’t far of a what modern paparazzi is to the stars.