What is the first note of a scale?

The first note of a musical scale depends on the key you're in. For instance, if you're in the key of A, the first note, known as the root, would be A. If you're in the key of F#, the root would be F#. No matter if you're playing the major scale, the minor scale, the blues scale, or any other scale, the root always matches the chord you're playing over.