1. Drums: The drummer is responsible for providing the foundation and pulse of the music. They use a variety of techniques, including using the bass drum, snare drum, hi-hat cymbals, and various other drums and percussion instruments to create rhythmic patterns.
2. Bass guitar: The bassist plays an instrument with four or five strings that typically plays the lowest notes within a jazz ensemble. The bassist's role is to provide a solid low end and support the harmony.
3. Piano: The pianist is usually the main harmonic instrument in a jazz band. They provide chords, comping (short, rhythmic chords), and solos.
4. Guitar: The guitarist can be used for chords, comping, and occasionally soloing. In jazz, the guitarist often plays a role in "comping" along with the pianist, creating a fuller harmonic sound.
5. Sometimes, other instruments like the Hammond organ or a vibraphone may be added to the rhythm section, especially in a big band setup.
This instrumentation can vary depending on the style of jazz, the size of the band, and the preferences of the musicians involved.