What is a key? Technically speaking, when playing traditional music, we would be more accurate if we referred to a tune’s modality (i.e. the notes/pitches that the melody centres around, the “home note”) in terms of modes, rather than keys. But understanding a key in basic terms is an essential jumping off point for exploring modes. So, let’s look at keys. In western musical theory there are 12 major keys. That is to say, there are 12 different kinds of note arrangement that pertain to a “major scale”.

Read more: Keys and Modes and Shouts, Oh My! – OAIM

Another useful table: