A jam session is a musical event where musicians, often improvising, play together without any planned arrangements or set list. It's an opportunity for artists to collaborate and create music spontaneously in front of an audience or among themselves. The term "jam" comes from the slang expression meaning "to improvise," while "session" refers to a period of time dedicated to creating music together. Jam sessions can occur in various settings, such as concerts, clubs, studios, and even impromptu gatherings, and are popular among musicians of all genres, from jazz to rock to blues.