The drums and bass both supply a rhythmic pulse for the music, and the bass instrument supplies a harmonic foundation with a bassline. The types of basslines performed by the bass guitarist vary widely from one style of music to another. Despite all of the differences in the styles of bassline in most styles of popular music, the bass guitarist fulfills a similar role: anchoring the harmonic framework (often by emphasizing the roots of the chord progression) and laying down the beat (in collaboration with the drummer). The importance of the bass guitarist and the bass line varies in different styles of music. In some pop styles, such as 1980s-era pop and musical theater, the bass sometimes plays a relatively simple part, and the music forefronts the vocals and melody instruments. In contrast, in reggae or funk, entire songs may be centered around the bass groove, and the bassline is very prominent in the mix.