Mozzarella is an Italian fresh cheese made from water buffalo or (more often outside of Italy) cows milk, the second used for most types of pizza.

Mozzarella is available in fresh (also called fior di latte), smoked (also called provola), and reduced-moisture packaged varieties. To preserve natural consistency (for no more than a couple of days), fresh mozzarella is delivered in its own liquid (whey).

The production of mozzarella involves the mixture of curd with heated whey, followed by stretching and kneading to produce a delicate consistency -- this process is generally known as pasta filata. According to the Mozzarella di Bufala trade association, "The cheesemaker kneads it with his hands, like a baker making bread, until he obtains a smooth, shiny paste, a strand of which he pulls out and lops off, forming the individual mozzarella." Mozzarella di Bufala Campana trade organization (Retrieved May 8, 2005) It is then typically formed into ball shapes or in plait. In Italy, a "rubbery" consistency is generally considered not satisfactory; the cheese is expected to be softer.

It has been said that the name "mozzarella", which is clearly derived from southern Italian dialects, was the diminuitive form of mozza (cut), or mozzare (to cut off). Other theories describe its origins as a minor preparation of "scamozza" (Scamorza cheese), which in its turn probably derives from "scamozzata" ("without a shirt"), with allusion to the fact that these cheeses have no hard surface covering typical of a dry cured cheese.

It is alternatively argued that the cheese originated in a 12th century monastery, whose members gave out homemade "mozza" or "provatura" on bread to visitors. These handouts were probably buffalo-milk "ricotta", from which modern mozzarella probably developed as a by-product. The term "mozzarella" is mentioned in cookbooks dating from the 16th century.