What is a Key?

Sure, what key is it in? Make a request at any venue in Key West and someone in the band will say “What key is it in?” Heck, I utter that phrase myself at least a few times a night!

What does it mean to be in a key? As my good friend and sublime jazz drummer, Hal Howland, likes to say, “Talk music to me.” Hal is talking about Music Theory, the formal language of music. Music theory is the common language and set of rules used by musicians to describe, compose, or write the music they are playing. It includes categories such as scales, chords, sharps, flats, time signatures, expressiveness, and yes, key signatures. The word key is shorthand for key signature, and that contains answer to the question “what key is it in?”

So what is a key? Some say it’s the “most common” chord. And others say the same for the most common notes. A musician can get themselves into a bit of a mess on the bandstand by making these assumptions. Consider “Little Red Corvette,” by Prince, or “Blueberry Hill” by Fats Domino. They don’t start in “the key” of the song, but on the fourth note above it. In order to reliably play in the right key, you need to know three things: scales, sharps (and flats), and chords.

A scale describes the sequence of steps needed to traverse across a set of notes on an instrument (think moving from one fret to another on guitar, or to another key on a piano). Those steps include half-steps (two notes directly adjacent to one another) and whole steps (two notes with another in-between). The sequence of half-steps and whole-steps defines what notes to play in a scale or chord.

All notes are named in the “musical alphabet”: A-B-C-D-E-F-G . After G comes A again – so it keeps recycling every eight notes (known as an octave). Scales are a pre-defined set of those notes that can start on any letter.

Each scale has a pre-defined number of sharps or flats, making the NUMBER of those the primary answer to the question “what key is this in?” Professional musicians will often put up two fingers on stage to indicate the key of D, three for the key of A, and so forth.

The final clue to the key of the song is the chords to be used. Chords are combinations of notes from the scale played at the same moment. The simplest of those is the major chord which is made up of the first, third, and fifth notes of the scale, played together. We can extend these chords by adding the other numbers. We can also modify the chords by adding a sharp or a flat in a specified location.

So, there it is. The answer to “what key is it in?” depends on the number of sharps and flats that are required to stay within the whole-step/half-step formula. It guides us on note selection for scales, solos, and melodies, and then defines how the chords are to be played.

Of course, like with any theory, there are exceptions and additions. If you are interested in reading more, “Tonal Harmony” is one of the standard theory textbooks out there. It’s only 700 pages!

For now, go have some fun and ask a musician to play the song in seven sharps (and make sure to drop a nice tip in their bucket, if they do it)!