Tense, bluesy, and commanding. Wants to resolve to the tonic.
The B Dominant 7th chord (B7) is built on the root note B with component pitches B, D#, F#, A. Formula: [0 - 4 - 7 - 10 semitones]. Category: Dominant 7th (4 tones). Primary genres: Blues, Jazz, Rock and Roll, Funk.
Notes in this chord: B - D# - F# - A
Use as the V chord to create a strong pull back to your I chord.