Paparazzi, plural of paparazzo, are photographers who pursue and often stalk celebrities in order to get photographs or videos of them in both their private and public lives.
Paparazzi photographers work independently or may be hired by a celebrity photo agency. Most photographers sell their photographs or videos within 24 hours of being shot to magazines and newspapers.Slate: How Do the Paparazzi Sell Their Pics? (June 3, 2005)
Origin
The term paparazzi originated from Italian filmmaker Federico Fellini. Fellini's 1960 film La Dolce Vita featured a character named Signor Paparazzo who was a photographer. The character of Paparazzo was based on real-life Italian photographer Tazio Secchiaroli.How Stuff Works: How Paparazzi Work