Music and Copyright

Copyright is a law that allows a creator of a piece of work certain rights for that works use. This applies to audio including certain music, soundtracks, theme songs, and much more.

Creative Commons

This is an organisation that allows the free use and distribution of pieces legally. This isn't an alternative to copyright, however, as the creator can modify their copyright terms with 'All Rights Reserved' or 'Some Rights Reserved'. 

Fair Use

Fair use is a more limited version of creative commons, as you can use some pieces but only for certain reasons. For instance, you can use a song in a video in it's for commentary or criticism reasons. Also, you can use certain pieces for parody reasons - which is, for instance, changing lyrics to a song for comedic purposes.

Royalty Free

Royalty free is a little bit similar to creative commons, and is often confused. However, there is a difference. RF is where you secure your use for a piece - most of the time using money - and, after that initial permission you can use that photo freely all you like.