The C7 chord is a type of seventh chord built on the root note C. It consists of four notes: C, E, G, and B♭. The addition of the B♭ note gives the chord its distinctive sound, making it a dominant seventh chord. This chord is commonly used in various music genres, including jazz, blues, and rock. In music theory, the C7 chord functions as a tension-building chord that typically resolves to the F major chord. It is often used to create a sense of movement and anticipation in a musical progression, enhancing the overall emotional impact of a piece.