A dominant seventh chord is a type of chord commonly used in music, consisting of four notes: the root, major third, perfect fifth, and minor seventh. It is often notated as "V7" in a key, indicating its role as the fifth chord that leads to the tonic. This chord creates a sense of tension that resolves when moving to the tonic chord, making it essential in many musical styles. In Western music theory, the dominant seventh chord is crucial for establishing harmonic progressions. It is frequently found in genres like jazz, blues, and classical music, where it enhances the emotional impact of a piece. The unique sound of this chord contributes to its popularity among composers and musicians.