Chords are clusters of musical notes that, when played together, create a harmonious sound; they add complexity and depth to musical compositions. 3 chord songs are compositions composed primarily of just three chords. Some of these songs literally use only three chords, while others may include three chords in the main sequence of the song — the verses and refrains — but may add other chords into separate sections. In many popular forms of music like rock and roll or rhythm and blues, 3 chord songs are extremely popular for their simplicity and power. These songs may consist of all major chords, which have a warm and happy sound, or they may include minor chords as well, which have a more subdued and mournful sound.
The basic components of 3 chord songs are the chords. A chord is a sequence of notes, which, when either played on an instrument or sung by three different voices, create a sound that's seamless. For example, playing the notes C, E, and G together sounds the C-major chord. Chords are usually made up of three notes, but just any three-note combination won't necessarily make a chord; if they don't fit together, they can create an unpleasant sound known as dissonance.
Most commonly, 3 chord songs are comprised of three major chords, which create a sound very familiar to fans of popular music like rock and roll and rhythm and blues. As an example, one popular rock song structure includes the C-major, F-major, and G-major chords. In technical terms, the C-major chord in that sequence is the tonic chord, the F-major chord is the subdominant chord, and the G-major chord is the dominant chord.
Represented in the Roman numeral terminology used by musicians, the sequence cited in the preceding paragraph is known as a I-IV-V sequence. It can be switched to any key, with the chords changing depending on the chosen key. Adding a minor chord or multiple minor chords to replace some of the chords in this sequence can add some depth and emotional power to 3 chord songs. For example, the sequence of A-minor, D-minor, and E-minor is a complementary way to create an effective sequence.
Much of the lure of rock and roll is grounded in its relatively simple structure, which paradoxically creates great emotional impact. Rock composers have used 3 chord songs as a way to create this impact. At different times in rock's history, there have been movements back to the simplicity of 3 chord songs whenever the genre has begun to be seen as a bit too refined. Punk rock bands often refuse to use more than three songs for this very reason.