Seven of Britain's largest music download sites have got together to promote a new "MP3 compatible" logo.
It aims to raise the profile of the open MP3 music format and show people what they can do with their downloads.
The trade body behind the initiative said it should also help consumers identify legal sites.
The Entertainment Retailers Association devised the logo, which emphasises the fact that MP3 files can be played on any digital player.
HMV, Woolworths, 7digital, Digitalstores, Tescodigital, Tunetribe, and Play.com have all signed up to the scheme, which will show consumers that the MP3 download will play on PCs, Macs, and portable music players.
According to October figures from the Official UK Charts Company, single track downloads were up 41% and album downloads increased 69% from the previous year.
7digital's Ben Drury said that online sales "have been booming" because users "love the freedom of MP3".
"The beauty of an MP3 file is that once you have bought it, you don't need to be a computer genius or a lawyer to make it work and you are not locked in to a relationship with a single retailer or hardware manufacturer," he said.
The British record industry's trade association, the BPI, is also backing the scheme.
Geoff Taylor, BPI chief executive, said: "This logo will not only help give consumers confidence that the music files they are buying will play on a wide range of devices, but will also help them know that they are legal and that artists are getting paid."
It is hoped the MP3-compatible logo will form the blueprint of an international standard and ERA is also seeking support from manufacturers of MP3-compatible digital music players.