A bass line is a musical part that provides the foundation for a song, typically played by instruments like the bass guitar or double bass. It consists of low-pitched notes that support the harmony and rhythm, helping to create a fuller sound. Bass lines are essential in various music genres, including rock, jazz, and pop. In addition to establishing the harmonic framework, bass lines often drive the groove of a piece, making it more engaging for listeners. They can vary in complexity, from simple repeating patterns to intricate melodies, and are crucial for connecting the rhythm section with the rest of the band.