Burritos are filled with savory ingredients, most often a meat such as beef, chicken, or pork, and often include other ingredients, such as rice, cooked beans (either whole or refried), vegetables, such as lettuce and tomatoes, cheese, and condiments such as salsa, pico de gallo, guacamole, or crema.

Before the development of the modern burrito, the Maya civilization of Mexico used corn tortillas as early as 1500 B.C. to wrap foods, with fillings of chili peppers, tomatoes, mushrooms, squash, and avocados. Historically, the Pueblo peoples of the Southwestern US also made tortillas filled with beans and meat sauce and prepared much like the modern burrito. But these preparations could also be said to be the origin of the simpler taco, rather than the modern burrito. Source: Wikipedia