How do companies pick music for their commercials?

Companies hire advertising agencies to create and produce their commercials. The advertising agencies select music that is appropriate to the product, the subject matter and/or mood, or desired emotional response of the commercial. Music for commercials can be original--that is, created specifically for the commercial being made) with music and lyrics written by composers and writers who are specialists in this field. The song would then be arranged, orchestrated, and recorded with professional musicians in a sound recording studio, then synchronized to a video track or to a voice-over track from an announcer or performer. Vocal solos or background harmonies may or may not be including, as appropriate. Commercial music may also not be original, but rather taken from an already existing recording. The source could be a recording of a past hit pop song, or a section of a Classical Music performance, or a dance club hit, or electronic music, etc. This technique is sometimes called a "needle drop", which refers to the process used in playing LPs vinyl recordings, where the needle on the tone arm of the turntable is manually placed on a certain cut or band on the record, or at a specific location in the grooves of the recording. Even though CDs or DVDs or digital music (MP3) would be used as sources today, this somewhat antiquated term is still used frequently in professional circles. This music from this needle drop would be played in the background, and it is more or less immaterial exactly what part of the composition or performance is used. The producer of the commercial simply wants a "bed" of music, some music, to be mixed into the background and never really featured in the commercial. The great majority of commercials made for U.S. advertising are produced and recorded in either New York or in Hollywood, although there is some considerable commercial music production in Chicago, Toronto, and other major North American cities.