A hamburger or hamburger is a sandwich consisting of one or more cooked minced meat (usually beef) placed in a roll or bun cut into thin slices. Small pies can be fried, barbecued or roasted in a pot. Hamburgers are usually served with cheese, lettuce, tomatoes, bacon, onions, pickles or peppers. Condiments, such as mustard, mayonnaise, ketchup, condiments, or "special sauces"; hamburgers, often topped with a piece of cheese on sesame bread, are called cheeseburgers.

The term "hamburger" can also be applied to patties alone, especially in the UK, where the term "Patty" is rarely used, or the term can even refer to ground beef only. The term can be prefixed with the meat or meat substitute used, such as "turkey burger", "buffalo Burger" or "vegetarian Burger".

Hamburgers are sold in fast-food restaurants, specialty restaurants and upscale restaurants (hamburgers may cost several times as much as fast-food hamburgers, but may be one of the cheaper options on the menu). There are many international and regional changes in hamburgers.