A quesadilla is the Tex-Mex dish of a flour tortilla filled with cheese, folded, and grilled.
The tortilla is heated until the cheese melts and the outside develops toasted spots. Tex-Mex versions frequently add seasoned beef, chicken, vegetables, or beans, although cheese remains the defining filling.
The word quesadilla is derived from queso, the Spanish word for cheese. In Mexico, quesadillas can be made with corn or wheat tortillas and may contain fillings beyond cheese; restaurant styles vary considerably by region.
A quesadilla differs from an enchilada because the tortilla is grilled rather than rolled and covered with chile sauce. It also differs from a taco, whose tortilla is normally folded around fillings without being sealed around melted cheese.