If you've read my other lesson on major scales, and even if you haven't, you probably know that there are 15 standard major scales that are played. These scales fit into the category of either one of the seven sharp keys, one of the seven flat keys, or the natural key of C. For example, the key of B has 5 sharps, as you can listen to here.

But there are actually more than 15 notes to play. For example, we use the key of Bb but not A#. So for these enharmonic keys, how do you know what notes they have, and how can you play them?