Essentially, an authorized music publisher grants rights (to broadcast, recreate, perform, or listen to a recorded copy of a copyrighted work) to a licensee (someone that wants to use the music). Here are some important terms to understand:
Mechanical Rights - A mechanical right is the right to record and distribute (without visual images) a song for private use. Mechanical rights or a mechanical license must be obtained in order to lawfully make and distribute records, CD's and tapes.
Master Use License - A copyright license to pay recording owners for music used in film, video, or TV soundtracks. There is no fixed fee for master use licenses.
Synchronization License - Synchronization (or sync) license is the licensed right for a film or other audiovisual medium to use music to synchronize (match) to recorded images in an audio-visual product. It can be a commercial, video game, film, TV show, music video, DVD or website, etc. A synch license usually produces a negotiated fee for certain rights depending on the usage. Synchronization rights are licensed by the music publisher to film and video producers, ad agencies or other program or product producers.