Wikipedia
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 Mylar (previously foil) packages, and do not require refrigeration.
Pop-Tarts is Kellogg's most popular brand to date in the United States, with millions of units sold each year. They are distributed mainly in the United States, but also in Canada, Finland, the United Kingdom, Ireland and New Zealand. Pop-Tarts was discontinued in Australia in 2005 and brought back in 2014 with two flavors: Strawberry Sensation and Chocotastic.
Pop-Tarts are produced in dozens of flavors, plus various one-time, seasonal, and "limited edition" flavors that appear for a short time.
Similar to Pop-Tarts is the Toaster Strudels brand, which launched in 1985 and are now a major competitor, in that they are about the same size and shape and are intended as a breakfast food and snack that is warmed in a bread toaster. However Pop-Tarts, being based on tart-style pastries, are thinner, do not need to be refrigerated, and the crust has very different texture and flavor. Toaster Strudel is based on a strudel-style pastry; additionally, the icing melts at a much lower temperature and is user-applied.