From Wikipedia: Pizza is a popular dish made with an oven-baked, flat, generally round bread that is covered with tomatoes or a tomato-based sauce and mozzarella cheese. Other toppings are added according to region, culture or personal preference.
Originating as a part of Italian cuisine, the dish has become popular in many different parts of the world. A shop or restaurant where pizzas are made and sold is called a “pizzeria”. The phrase “pizza parlor” is also used in the United States. The term pizza pie is dialectal, and pie is used for simplicity in some contexts, such as among pizzeria staff.