V7

V7 is a common designation in music theory, where it refers to the dominant seventh chord built on the fifth scale degree of a key. In standard major/minor keys, the V7 chord consists of a root, a major third, a perfect fifth, and a minor seventh above the root. For example, in C major the V7 chord is G-B-D-F. This chord creates a strong sense of tension that resolves downward by step to the tonic chord (I or i), a foundational device in Western tonal harmony.

In notation and practice, V7 is typically written as V7; inversions can be implied or indicated with figures or slash notation. In classical practice, the V7-I cadence is a primary cadence. In jazz, V7 is often altered (for example V7b9, V7#5) and can be extended to include additional tensions or suspended notes, with voice-leading designed to resolve to I.

Other uses: The designation V7 may also appear in contexts outside music as a model name, version number, or product code; such uses are varied and not tied to a single standard meaning.