The Csus4 chord, or C suspended fourth, is a type of musical chord that replaces the third note of the C major chord with the fourth note. In the case of Csus4, the notes are C, F, and G. This creates a suspended sound, giving the chord a sense of tension that often resolves back to a major or minor chord. Csus4 is commonly used in various music genres, including rock, pop, and jazz. It adds a unique flavor to chord progressions and can enhance emotional expression in a piece. Musicians often use it to create anticipation before resolving to a more stable chord.