The calzone is a Italian style turnover which is traditionally created by folding a pizza in half prior to baking. The salted bread dough crust of calzoni is folded into a half-circle shape to create a pocket for warm gooey cheese and other pizza toppings. The outer edges of calzoni are sealed by joining two pieces of dough together with a egg wash mixture to properly enclose all of the fillings before it can be baked. Once prepared, the calzone is baked, preferably on a pizza stone, until the outer crust appears crisp and golden brown. Immediately after baking, the calzone is then brushed with a blend of olive oil and spices. This "inside out pizza" has been satisfying "crust lovers" for over two centuries.
Sources: http://www.foodnetwork.com/recipes/jamie-oliver/calzone-recipe2.html
http://www.pizzamanual.com/pizza.asp?name=calzone&cat=6&con=0
http://www.pizzamanual.com/pizza.asp?name=calzone&cat=6&con=0