Chord progressions are the basis of harmony in songs and there are many common or standard progressions that are useful to know.
(a “chord progression“ is simply a sequence of chords: one chord after another.)
Chord progressions are often thought about in terms of the chord roles in a particular key, rather than the exact chords played.
For example, we talk about a “1 4 5” progression (or “I IV V“) rather than a “C F G” progression, because playing the chords with these scale degrees will produce the same characteristic sound in every key.
There are music theory rules for what chords can or should follow each other, and these are helpful to know because:
- it makes it quicker to work out the chords to a song by ear
- it helps you find appealing sounds when writing songs
However, the ultimate guide must always be your ear, and you can come up with some great music just by following your ear to choose which chord should come next.