A jam session is a musical act where musicians play by improvising without extensive preparation or predefined arrangements. Jam sessions are often used by musicians to develop new material, find suitable arrangements, or simply as a social gathering and communal practice session. Jam sessions may be based upon existing songs or forms, may be loosely based on an agreed chord progression or chart suggested by one participant, or may be wholly improvisational. Jam sessions can range from very loose gatherings of amateurs to sophisticated improvised recording sessions intended to be edited and released to the public.
Jam Sessions are an old Jazz tradition, and serve several important functions in the Jazz community. They allow emerging players to test their skills in front of an audience. Jam sessions also provide an opportunity for "cutting contests" where musicians vie for dominance by comparing their imaginations and improvisational skills in a live face-to-face situation. Also, Jam sessions allow musicians new to the area to network, and show what they have to offer.