In music, especially modern popular music, a slash chord or slashed chord, also compound chord, is a chord whose bass note or inversion is indicated by the addition of a slash and the letter of the bass note after the root note letter. It does not indicate "or".For example, a C major chord (C) in second inversion is written C/G or C/G bass, which reads "C slash G", "C over G" or "C over a G bass". Some chords may not otherwise be notated, such as A♭/A. Thus, a slash chord may also indicate the chord form or shape and an additional bass note.
In popular music, where the exact arrangement of notes is less important than some other forms, slash chords are generally used only when the specific bass note is important. A common example in guitar based music is in the I-V-vi progression, in which the V chord is a passing chord. By placing the third of the V chord in the bass, a descending scale, also known as a walkdown, is created in the bass. For example, in the key of G major this would be the chords G, D/F♯, Em. That progression has the descending bassline G, F♯, E. This type of slash chord contains diatonically occurring notes. In traditional Classical notation it would be written using figured bass symbols. Another commonly used type of slash chord in chord progressions is the minor key progression i – i/VII bass – iv/VI bass – V. In the key of A minor, this chord progression would be notated A minor, A minor/G, D Minor/F, E major (or E7). This descending bassline moving diatonically from i to V is a stock feature in popular music that is used in numerous songs.