A chord is a group of three or more notes played simultaneously. Different types of chords can be formed by using different combinations of notes. The most common type of chord is 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 (root note), 3 (third) and 5 (fifth) degrees of the major scale, so the chord formula for the major chord is:
The C major chord is constructed from the C major scale. When the major chord formula is applied to the C major scale, it can be seen that the C major chord contains the notes C, E and G.
The chord symbol for a major chord is just the letter name of the chord, e.g., the chord symbol for the C major chord is C. It is common practice to refer to a C major chord as the C chord. This abbreviation applies to all major chords.