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More about keys

So the root note and the corresponding scale (major or minor!) are very important in music. The scale used in a song determines the key.

A key is a root note followed by major or minor.

A song can be in the key of C major. It then consists of a melody with notes from the C major scale, and chords that are built up from the notes of the C major scale. A song can also be in the key of A minor. In the same way the key can be "C minor", or "F major", or "G major", etc.

We'll get to those other keys (that is, not C major or A minor) later.

"Extra" tones

It is common for compositions to use tones that do not appear in the scale (in the melody and accompaniment). These are then exceptions, these tones do not influence the key. You determine the key based on the dominant root note and scale.

Transposing

Imagine that a song is in the key of C major, and the singer asks to play the song e.g. two tones higher, because that suits his or her vocal range better.

In such a case, all the tones in the song, both the melody and the accompaniment, must be played two tones higher. The relationship between the tones remains exactly the same. Everything remains the same, except that everything is two tones higher. This is called transposing.

When transposing two tones up, you transpose the song from the key of C major to the key of E major (from C to E is two whole tones).

On guitar this is quite simple: you play everything four frets higher (one fret is a a semitone, two frets is one tone > four frets is two tones):

Original melody in C

Transposed melody in E: four frets higher

Note that in the sheet music of the second melody a lot of sharps(#) are used. If you transpose a melody, you normally need sharps or flats. Don't worry, we'll get to that soon!

Modulating

Transposing should not be confused with modulating. You speak of modulating when you change key during the song. For example, you can modulate in an intermediate section of a song in D minor to B minor, which gives a very dramatic effect. After the intermediate section, you modulate back to D minor. The composition then consists of two keys. The dominant key here is D minor, because that is where it started and comes "home".

Another common example is going “a tone higher”. At the end of a song, a well-known sing-along chorus is repeated, and at the end the whole chorus is modulated a tone higher.
When modulating, you do the same thing as transposing. However, it is part of the composition, and just "temporary".

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