A composer will get mechanical royalties for the sale of the recorded compositions in CD form and for airplay and will get licensing income from other uses, ie film, TV, commercials, ring tones etc.

so it depends on how many units are sold, and if there is a market for synchronization usage.

If you go through a big publisher, they will flog the music more effectively, but will get a piece of the action. You would also need to recoup any advances before you see cash flow.

Two types of royalties exist:

Mechanical - paid by the record company to the songwriter for the right to copy his/her work (ie, pressing albums). In the UK, 8.5% of PPD which stand for roughly 25p per disc. But you have to recoup, and in practice few are those who see money from their first album (apart from advances) especially in the case of a new artist signing with a major. Even if you sell million copies worldwide, the record company's marketing investmeant will be relative and sometimes enough to eat your share.

Performance - paid by public bodies (radio stations, pubs, or any body that plays music in public/ to the public) to the songwriter. And this is really where you see the money from. In the UK 242,500,000 pounds were distributed in 2002 between 40,669 songwriters - an average of about 6000 pounds per member. A hit song will generate a figure which is much higher than that (minus publisher share, if any, which is 10%-50%).

In the US things are roughly the same, only you say tomato and we say tomato.