Bumper music, or a bump, is a term used in the radio broadcasting industry to refer to short clips of signature

Signature song

A signature song is the one song that a popular and well-established singer or band is most closely identified with or best known for, even if they have had success with a variety of songs...

 or theme music

Theme music

Theme music is a piece that is often written specifically for a radio program, television program, video game or movie, and usually played during the title sequence and/or end credits...

 used to buffer transitions between programming elements. Bumper music is commonly employed when a syndicated program takes a break for local station identification

Station identification

Station identification is the practice of radio or television stations or networks identifying themselves on air, typically by means of a call sign or brand name...

 or "goes to a radio commercial

Radio commercial

Commercial radio stations make most of their revenue selling “airtime” to advertisers. Of total media expenditures, radio accounts for 6.9%. Radio advertisements or “spots” are available when a business or service provides valuable consideration, usually cash, in exchange for the station airing...

." More often than not called a "Bump" in today's radio. It is also referred to as "rejoiner music" when the bumper music marks the end of a local break on a radio network

Radio network

There are two types of radio networks currently in use around the world: the one-to-many broadcast type commonly used for public information and mass media entertainment; and the two-way type used more commonly for public safety and public services such as police, fire, taxicabs, and delivery...

.