The most common type of taco in the US is the hard-shell, U-shaped version, first described in a cookbook in 1949. This type of taco is typically served as a crisp-fried corn tortilla filled with seasoned ground beef, cheese, lettuce, and sometimes tomato, onion, salsa, sour cream, and avocado or guacamole.

Tacos are thought to come from Mexico, long before the Spanish arrived. Ancient Mexicans used freshly made, soft, flat corn tortillas and gave them with fillings like fish and cooked organs. It was a staple meal that provided vital nutrients and energy to those who consumed it.