A pizza pan is used to bake pizza. It is usually an aluminum disk, about 18" (450 mm) in diameter, with lots of small holes to let moisture out for a crispy crust. Sometimes a mesh of steel wire is used.
With completely uncooked pizza dough, a cookie sheet can be substituted. (this alone will not produce a crispy crust) With a partially cooked crust, the pizza can be placed on an oven rack without any pan at all.
An aluminum pizza pan should not be cleaned with caustic oven cleaner, as the resulting chemical reaction will damage it.