Tequila is a Denomination of Origin spirit, produced legally in only five Mexican states: Jalisco, Nayarit, Guanajuato, Michoacan and Tamaulipas. To be classified as tequila, the product must be made from at least 51% blue agave.
The remaining 49% can be made from maize (corn) - this type of tequila is commonly known as mix to.
Mixto is to 100% tequila as “sparkling wine” is to champagne. Premium tequilas, like Chinaco, are made with 100% blue agave and bottled only in Mexico.