A jam session is a musical event, process, or activity where musicians play (i.e. “jam”) 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. To “jam” is to improvise music without extensive preparation or predefined arrangements.