The McMuffin is the brand name for a breakfast sandwich available at McDonald’s consisting of a slice of Canadian bacon, a grill-cooked egg, and a slice of cheese on a buttered, toasted English muffin. A sausage patty may also be selected in place of the Canadian bacon (in which case it would be called a Sausage McMuffin with Egg).
Breakfast is the first meal of the day, typically eaten in the morning. The word derives from the idea of breaking the involuntary fast of sleep.