Masa is the traditional dough used to make corn tortillas. It’s made from dried corn that has been nixtamalized, which is a process in which dried corn kernels are soaked and cooked in an alkaline solution to loosen the hulls and make the corn softer for grinding. Masa harina, on the other hand, is a flour that’s made from dried masa dough. Masa harina is commonly used to make corn tortillas, too, but it’s also used to make tamales, tamal de cazuela, pupusas and arepas.