Egg cookers are used to cook eggs. Nowadays, modern, electrically run versions are most commonly used. Their predecessors would be simple water containers in which the eggs are cooked for a certain amount of time.
In order to prevent an egg from bursting, the large end of the egg should be poked with a needle so any air contained in the egg can escape.
An electric egg cooker is usually composed of a heater in which the water is boiled, an egg rack that usually holds 3, 6 or 7 eggs (depending on model) as well as a lid featuring a calibrated opening that regulates the amount of steam that evaporates from the and also doubles as a splash and heat guard.