Pop-Tarts is a brand of rectangular, pre-baked, convenience food toaster pastries that the Kellogg Company introduced in 1964. Somewhat similar to a contemporary English mince pie tart, Pop-Tarts have a sugary filling sealed inside two layers of rectangular, thin pastry crust. Most varieties are also frosted. Although sold pre-cooked, they are designed to be warmed inside a toaster or microwave oven. They are usually sold in pairs inside foil packages, and do not require refrigeration.