A toaster is an electric small appliance designed to expose various types of sliced bread to radiant heat, browning the bread so it becomes toast.
The most common household toasters are the pop-up toaster and the toaster oven. A third type, most commonly found in restaurants, has a metal-mesh conveyor belt that moves the bread past constantly-powered heat elements.
n pop-up or automatic toasters, a single vertical piece of bread is dropped into a slot on the top of the toaster. A lever on the side of the toaster is pressed down, lowering the bread into the toaster and activating the heating elements. The length of the toasting cycle (and therefore the degree of toasting) is adjustable via a lever, knob, or series of pushbuttons, and when an internal device determines that the toasting cycle is complete, the toaster turns off and the toast pops up out of the slots.
In earlier days, the completion of the toasting operation was determined by a mechanical clockwork timer; the user could adjust the running time of the timer to determine the degree of toasting, but the first cycle produced less toasted toast than subsequent cycles because the toaster was not yet warmed up. Toasters made since the 1930s frequently use a thermal sensor, such as a bimetallic strip, located close to the toast. This allows the first cycle to run longer than subsequent cycles. The thermal device is also slightly responsive to the actual temperature of the toast itself. Like the timer, it can be adjusted by the user to determine the doneness of the toast. Toasters may also be used to toast other foods such as teacakes, toaster pastry, potato waffles, and crumpets, though resultant accumulation of fat and sugar inside the toaster can contribute to its eventual failure.
Among pop-up toasters, those toasting two slices of bread are more purchased than those which can toast four. Pop-up toasters can have a range of appearances beyond just a square box, and may have an exterior finish of chrome, copper, brushed metal, or any color plastic. The marketing and price of toasters may not be an indication of quality for producing good toast. A typical modern two-slice pop-up toaster can draw from 600 to 1200 watts.
Beyond the basic toasting function, some pop-up toasters offer additional features such as: