Pizza cheese encompasses several varieties and types of cheeses and dairy products that are designed and manufactured for use specifically on pizza. These include processed and modified cheese such as mozzarella-like processed cheeses and mozzarella variants. The term can also refer to any type of cheese suitable for use on pizza. The most popular cheeses used in the preparation of pizza are mozzarella (accounting for about 30%), provolone, cheddar and Parmesan. Emmental, Romano and ricotta are often used as toppings, and processed pizza cheeses manufactured specifically for pizza are mass-produced. Some mass-produced pizza cheeses are frozen after manufacturing and shipped frozen.