Harmony can be thought of as the notes that support and add character to a melody. The basic building blocks of harmony are chords. A chord is a group of notes played simultaneously (e.g., strumming on a guitar). Like scales, there are many different types of chords, the most common being the major chord. All major chords contain three notes, taken from the major scale of the same letter name.
These three notes are the 1 (first), 3 (third) and 5 (fifth) notes of the major scale, so the chord formula for the major chord is: 1 3 5. If these notes were taken from the C major scale the chord would be a C major chord, usually just called a C chord.
Chords are represented by symbols usually written above the vocal melody on sheet music. The symbol for a C chord is the letter C (see following diagram). The symbol for a D (major) chord is the letter D. The symbol for an E flat chord would be Eb.
The C major chord is constructed from the C major scale. Using this chord formula on the following C major scale, it can be seen that the C major chord contains the notes C, E and G.
The following example demonstrates a short melody in * time in the key of G accompanied by three major chords – G, C and D. The chord symbols for these chords are written above the melody. Notice also the key signature and the time signature at the start of the music. Listen to the example to hear the effect created by the combination of melody and chords.