A Pop-Tart is a flat rectangular toaster pastry approximately 3 in (75 mm) by 5.5 in (115 mm), made by the Kellogg Company. Pop-Tarts have a sugary filling sealed inside two layers of rectangular, thin pastry crust; each layer of this crust is about 0.1 in (2 mm) thick. Most varieties have frosting, but some do not. They can be eaten without being warmed, but are often warmed inside a toaster. They are usually sold in pairs inside foil packages, and do not require refrigeration. _Wikipedia
Has become a generic term for any toaster pastries.