Today, September 5th, is National Cheese Pizza Day.
A cheese pizza would normally consist of the pizza sauce and cheese. Just cheese. Herbs may also be added, but cheese is the ingredient here.
Although the traditional pizza cheese is mozzarella, with buffalo mozzarella the best, a cheese pizza can, and often does, consist of a selection of cheeses. Cheddar cheese is popular, as this is a type that melts well, but plenty of others can be used, such as goat's cheese for a stronger flavour.
In Britain a cheese pizza is usually known as a Margherita, which may not be a strictly accurate usage of the name.