A toaster is a machine for toasting food such as sliced bread and bagels. Toasted bread is called toast. Other toastable products may be described as toaster pastry.
A typical toaster works by heating the bread. The heat is usually produced by conducting electricity through nichrome wires (Joule-effect). The toasting process consists of reducing the bread's water content (originally ~35% of total weight), raising its temperature, and slightly charring its surface.