There are 12 major keys one can play in (more if you count enharmonic keys, but we won’t here). To learn those 12 keys, it is useful to learn the “Circle of Keys”. It is often called the “Circle of 5th” or the “Circle of 4ths”. It is all the same thing — just depends which way you move on the circle. Watch this 5-minute video on the circle:

Tags: circle of keys