The major and minor chords you already know are made up of three notes—the root (or first note in the corresponding scale), third, and fifth. The third of a chord is what gives major and minor chords their character. The major third in a major chord gives it that distinctive “happy” sound, while the minor third in a minor chord gives it a distinctive “sad” sound. A sus4 (or “suspended fourth”) chord substitutes the fourth note of the chord’s corresponding scale for that all-important third. The lack of the third’s distinctive sound means that sus4 chords can be played with or substituted for either major or minor chords. Sus4 chords are the most common sus chords, heard in countless classic songs like Tom Petty’s “Free Fallin’,” the Beatles’ “A Hard Day’s Night,” and many others.
Let’s see what these chords sound like by comparing an E and an Esus4 chord. To play the Esus4, start with an E chord and lay your pinky down on the second fret of the third string, one fret above where your index finger is when playing the E chord. The “sus4” part of this chord is the note you’re playing with your pinky, and it’s replacing the note your index finger plays in an E chord—the third. Shifting between these two chords already gives you a great-sounding effect (Example 1). This chord change is similar to the one used in the opening of the Eagles’ “Peaceful Easy Feeling.”