If you are shooting indie projects or editing wedding videos, you know how hard it is to find good music for reasonable prices. This is why many opt for Royalty Free music licensing. This is very similar to Royalty Free photography – you pay a lump sum and can use the music regardless of how many seconds of it you need / how it will be used / where geographically it will be played. (there are different fees per different uses, but the idea is similar – a one time buy out).
Like with anything off the shelf, Royalty Free music is not tailor made for a specific movie or a specific scene. Tumbler David Marino has a funny flow chart describing how he handles Royalty Free music in his movies.
If Royalty Free is still too expensive for you, and you want FREE, Kevin MacLeod has a great library and he only requires attribution to use it. (We have used his music too in our white background tutorial way back).
The fact that his music is both good and free makes Kevin one of the most prolific composers on IMDB with over 1080 titles (21 of which in various stages of production right now).
You can download a bigger version of this chart here.