Cheddar cheese is branded as sharp or extra-sharp when it is aged and its flavors become more concentrated and biting.

Generally, the older the cheese, the sharper it will be, as enzyme-producing bacteria break down the protein and fat of the cheese and give it what we metaphorically call a sharp flavor.

The taste difference between mild and sharp cheddar is startling, but it's not an exact science and depends as much on the way a cheese is produced as how long it has been aged.