Hamburgers.

Hamburgers are usually a feature of fast food restaurants. The hamburgers served in major fast food establishments are usually mass-produced in factories and frozen for delivery to the site.[25] These hamburgers are thin and of uniform thickness, differing from the traditional American hamburger prepared in homes and conventional restaurants, which is thicker and prepared by hand from ground beef. Generally most American hamburgers are round, but some fast-food chains, such as Wendy's, sell square-cut hamburgers. Hamburgers in fast food restaurants are usually grilled on a flat-top, but some firms, such as Burger King use a gas flame grilling process. At conventional American restaurants, hamburgers may be ordered "rare" (occasionally requiring the signing of a waiver), but normally are served medium-well or well-done for food safety reasons. Fast food restaurants do not usually offer this option.

The McDonald's fast-food chain sells the Big Mac, one of the world's top selling hamburgers. Other major fast-food chains, including Burger King (also known as Hungry Jack's in Australia), A&W, Culver's, Whataburger, Carl's Jr./Hardee's chain, Wendy's (known for their square patties), Jack in the Box, Cook Out, Harvey's, Shake Shack, In-N-Out Burger, Five Guys, Fatburger, Vera's, Burgerville, Back Yard Burgers, Lick's Homeburger, Roy Rogers, Smashburger and Sonic also rely heavily on hamburger sales. Fuddruckers and Red Robin are popular hamburger chains that specialize in mid-tier "restaurant-style" variety of hamburgers. The "slider" style of mini hamburger is still popular regionally in the White Castle and Krystal chains.
Some North American establishments offer a unique take on the hamburger beyond what is offered in fast food restaurants, using upscale ingredients such as sirloin or other steak along with a variety of different cheeses, toppings, and sauces. Some examples would be the Bobby's Burger Palace chain founded by well-known chef and Food Network star Bobby Flay.
Hamburgers are often served as a fast dinner, picnic or party food, and cooked outdoors on barbecue grills.
Raw hamburger may contain harmful bacteria that can produce food-borne illness such as Escherichia coli O157:H7, due to the occasional initial improper preparation of the meat, so caution is needed during handling and cooking. Because of the potential for food-borne illness, the USDA recommends hamburgers be cooked to an internal temperature of 170 °F (80 °C). If cooked to this temperature, they are considered well-done.[26]
A high-quality hamburger patty is made entirely of ground (minced) beef and seasonings; this may be described as an "all-beef hamburger" or "all-beef patties" to distinguish them from inexpensive hamburgers made with added flour, textured vegetable protein, ammonia treated defatted beef trimmings what the company Beef Products Inc, calls “lean finely textured beef”,[27][28] Advanced meat recovery (see below: Health-related controversies) or other fillers to decrease their cost. In the 1930s ground liver was sometimes added to the patties. Some cooks prepare their patties with binders, such as eggs or bread crumbs. Seasonings are also commonly included with the hamburger patty, most commonly salt and pepper, and others such as parsley, onions, soy sauce, Thousand Island dressing, onion soup mix, or Worcestershire sauce. Many name brand seasoned salt products are also used.