A C# Dominant Seventh Chord is a four-note chord that consists of the root note C#, the major third E#, the perfect fifth G#, and the minor seventh B. This chord is often notated as C#7 and is commonly used in various music genres, including jazz and blues, to create tension that resolves to other chords. In music theory, the dominant seventh chord plays a crucial role in establishing harmonic movement. It is built on the fifth degree of a scale, making it essential for creating a sense of resolution in progressions. The C# Dominant Seventh Chord can lead to the F# major chord, which is its tonic in the key of B major.