Cotija cheese is a Mexican dry grating cheese made with cow's milk and is similar to Parmesan. In the U.S. you may find a fresher, softer version, similar to Feta but in Mexico this salty cheese is typically aged at least 100 days. Cotija is named after the Mexican city of Cotija, Michoacán.
The aged version is referred to as "anejo". This is not a cheese you would add to your cheese board but you would typically use it crumbled or grated over tacos, beans, soups or casseroles.
Look for Cotija cheese in many well-stocked grocery stores as well as most Mexican markets. You can also purchase cotija online at Amazon.com:
El Mexicano Queso Cotija.
Cotija is also available, ground. Los Altos Cotija Mexican Cheese is aged, salty, and sharp conveniently ground to a finer texture for use in soups, pastas and moles or as a topping to some of your favorite pizzas, pastas and more. Queso Cotija Molido is available at Amazon.com