What is a “Key”?

I know what some of you might be thinking reading this heading… “A key is the little piece of metal with teeth that I put in the lock to open the door.” That’s true.  But in a musical context a key is something else entirely.  However, not unlike the key you might have been thinking of, musical keys can unlock all kinds of potential.  You’ve probably heard someone say ‘this song is in the key of G major’ before.  What does that mean? 

In Western music, we’re generally dealing with 12 possible notes.  When we say that we’re playing within a certain key, we’re saying that we’re dealing with a specific set of seven notes that are organized within a scale to determine the key.  Hold on… what’s a scale? A scale is just a grouping of notes organized in a pattern that have a specific starting point and an ending point that’s an octave (or eight notes) higher. 

Let’s start with a C major scale.  This scale is a great one to start with because all of the notes are what we call ‘natural notes’ (meaning there are no sharps or flats AKA accidentals).  The C major scale looks like this: C D E F G A B C.  When we’re dealing with this particular grouping of notes, you are playing in the “key” of C major. 

If we suddenly change the key to G major we are now dealing with the G major scale which looks like this: G A B C D E F# G.  Do you notice anything different about these two scales? 

The pattern and the distance between each note is identical in both of these scales.  They’re both major scales.  In a major scale the pattern goes like this: whole step, whole step, half step, whole step, whole step, whole step, half step.  When we talk about these “steps” we’re talking about the distance between notes.  A half step means that you’re approaching the next closest note.  If you look at the C major scale, the E note and the F note are a half step apart.  If you were holding your guitar that would mean the two frets were adjacent.  So as an example if I play an E note on the 7th fret of the A string, I know that the note right next to it on the 8th fret is an F.  A whole step is the distance of two half steps.  So within the same scale, if I’m holding my guitar and I fret a C note on the 3rdfret of the A string, I know that the note on fret 5, which is two half steps away, is a D note. 

Let’s go back to the question about what’s different between these two scales.  If you’re sitting there thinking ‘I’m pretty sure it’s the number sign right next to the F in the second one’ you nailed it!  That number sign is a form of musical notation to denote a sharp note.  The difference between the C major scale and the G major scale is that the G major scale contains one accidental (i.e. sharp note) in the key.  You have an F sharp instead of an F. 

Why do we illustrate this point?  Because even though the scale is organized in the same way, contains the same number of notes, and those notes are the same distance apart, the notes we are working with are different in a different key.  This is an important way for musicians to communicate about which notes are involved in a particular piece, or in some cases just a particular section of music. 

We’re just scratching the surface here.  When you start looking at the distance between notes, you begin to understand the concept of intervals.  When paying attention to particular intervals you begin to understand chord construction and chord extensions.  This is really helpful because you understand why a chord like F#min7b5 would be diatonic (meaning… containing only notes within key) to the key of G major, but not so for the key of C major. 

Cheers guys and keep exploring those frets!!!   

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