What is the V7 chord?

The V7 chord, or dominant seventh chord, is a four-note chord built on the fifth degree of a scale. It consists of a root, major third, perfect fifth, and minor seventh. In the key of C major, for example, the V7 chord is G7, which includes the notes G, B, D, and F. This chord creates a strong resolution back to the tonic chord (I) due to its tension and dissonance.