In my last article, I talked about the 5 Ways Nashville Numbers Will Change Your Life. So, if you don't even know what numbers are, start there. Otherwise, let's look at the basics of the system. Almost all music is a clever arrangement of 7 notes. Pick almost any song you can think of, and you'll hear a group of 7 notes that are used to create chords, melody lines, harmony parts, guitar solos, etc. Just 7 notes! It's pretty amazing really. This grouping is called a "key". So, you have the key of D, the key of G, etc.