What is the "Key" of a song?

"Key" can refer to a several things. They include:

1. The key signature or parent major scale
2. The root
3. The first note or chord of a song.
4. The mode

In most cases when a guitar player says "key," he is referring to the chord or note that sounds like the tonal center of the song. This root may not always match the actual key which should be based on the parent major scale. For example, "Gloria" by Van Morrison revolves around, and resolves on E, but the chords are derived from the A major scale's V IV and I (this produces E mixolydian mode).

Sometimes guitar players will name a key simply by whatever note or chord is first. For example, "Sweet Home Alabama" by Lynyrd Skynyrd starts on D, but G is the strongest tonal center, and the chords are derived from the G major scale's V IV and I. The majority of the melodies, riffs and solos are based on G major pentatonic and G major scale. It's more correct to say the song is in G, but most players call it D.

As you can see, guitar players have different meanings for the word "key," and musicians can examine a song's structure from different perspectives. A good approach to learning guitar theory is to always start with the parent major scale, then identify which note is functioning as the root.

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Mr. Desi Serna (Google me!)
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