Synchronization rights

A music synchronization license, or "sync" for short, is a music license granted by the holder of the copyright of a particular composition, allowing the licensee to synchronize ("sync") music with some kind of visual media output (film, television shows, advertisements, video games, accompanying website music, movie trailers, etc.).
Copyright ownership.
The rights to a composition or the "song", which is different from the studio sound recording, are most often administered by the publishing company that represents the writer/producer. A sound recording has two separated copyrights: 
Sync negotiations and fees.
When an audio/visual project producer wants to use a recording in their work, they must contact both the owner of the sound recording (record label of the performer), and the owner of the composition (publishing company of the songwriter). In many cases, producers with tight budgets will elect to use a cover version of a particular song in order to save money on the master side. 
Once the producer has made an inquiry with the copyright administrator (and additionally the record label if they choose to use a famous recording), the rights holder or administrator issues a quote, usually for a "one-time fee" (often called the "sync fee" or the "front end"). Negotiations for the licensing fee typically address how the work is being used, the length of the segment, the prominence of the cue (whether used as background music, the title track during the credits, or other uses), and the overall popularity and importance of the song or recording. Another point of negotiation is whether the sync license constitutes a "buyout" (i.e. whether or not the entity that will ultimately broadcast the production will be required to pay "backend" (performance royalty) fees). 
Sync licensing fees can range anywhere from free, to a few hundred dollars, to millions of dollars for popular recordings of songs (when the producer must pay for both the use of the sound recording "master" as well as the composition).