An altered chord is a chord in which one or more notes from the diatonic scale is replaced with a neighboring pitch from the chromatic scale. According to the broadest definition any chord with a nondiatonic chord tone is an altered chord, while the simplest use of altered chords is the use of borrowed chords, chords borrowed from the parallel key, and the most common is the use of secondary dominants. As Alfred Blatter explains,"An altered chord occurs when one of the standard, functional chords is given another quality by the modification of one or more components of the chord."