Music fans have snapped up more than 10 million songs from Apple's iTunes music store in four months.
ITunes service has been hugely popular since it launched
Apple said the 10 millionth song bought from its online store for 99 cents (66 pence) was Complicated by Avril Lavigne.
The success of the iTunes music venture contrasts with other industry-backed, subscription-based music services.
It comes as the record industry steps up legal action against people accused of illegally sharing music online.
Easy to use
The iTunes store is widely seen as one of the most consumer friendly methods of buying music online.
It has become hugely popular since it was launched in May, partly due to the few restrictions on what people could do with the music they downloaded.
"Legally selling 10 million songs online in just four months is a historic milestone for the music industry, musicians and music lovers everywhere," said Apple boss Steve Jobs.
Backed by the five major record labels, Apple offers 200,000 songs at 99 cents. At the moment the service is only available to Mac users in the US, but a Windows version is due by the end of the year.
The iTunes store offers music fans a legal way to download songs over the internet, at a time when the record labels are trying to stop the millions of tunes shared without permission online.
The music industry blames a slump in CD sales on online file-sharing services. It is now taking legal action against individuals accused of downloading pirated music.
Other companies are trying to replicate the success of Apple's iTunes, moving away from subscription-based services.
The iPod has been upgraded
These have failed to attract music fans as they are seen as too complicated and expensive.
One service, BuyMusic.com, is selling music downloads for 79 cents per song and $7.95 per album.
In Europe, Virgin has just joined other companies in launching its own service, reselling licensed music from the British technology company OD2 for as little as 60 pence a track.
OD2 has a catalogue of over 200,000 songs and is the only European firm to have permission from each of the five major music labels to resell digital downloads.
Music to go
Apple is seeking to capitalise on the appeal of its music service by announcing new versions of its digital music player, the iPod.
The new model comes with a 40GB hard drive at a cost of US$499 (£399). which can hold as many as 10,000 songs.
Apple also sells a 10GB iPod for $299 (£249) and a 20GB one for $399 (£299).
"The iPod and the iTunes Music Store offer music lovers an unbeatable combination that our competitors can't even come close to," said Mr Jobs.