Although it is common today, even a few short years downloading music was not particularly common. Two things happened that forever changed the music industry, and allowed safe music downloading for the average user. The first was the introduction of mp3 compression technology. This is the sort of invention that took everyone by surprise, and allowed near-perfect quality music to be stored in files about a 10th of their original size, which removed the main barrier to trading online music: the large file sizes. Next came the advent of broadband internet access in many homes, which allowed users to exchange entire albums of mp3s in minutes. These two facts led to the proliferation of peer-to-peer file sharing, and the bonanza in safe music downloading that exists today.
The current state of affairs has created a situation where the music industry has become highly motivated to make downloading music legal. A point was reached where downloading music laws had become for the most part unenforceable, and the industry was concerned about how fragrantly and easily these downloading music laws were being violated.
What the music industry has attempted to do is to make some forms of downloading music legal. Sites have been set up in partnership with record labels in which a user pays for a song, as he rationally would, and then can download a high quality copy to his PC. To make downloading music legal, the record companies had to find a way to not only compensate the artists, but to try and prevent the spread of the files downloaded. How most of the sites (Apple's iTunes Music Store, Musicmatch) operate, then, is to place restrictions on the files downloaded from their central servers. Unlike peer-to-peer file sharing, to make downloading music legal the music stores offer their files from a fast, central server, and embed code in the music files that prevents them from being copied to more then 1 or 2 other computers.
Apple has done its part to make downloading music legal in two important ways. First, they created the ipod - the first and by far most popular hard drive based mp3 player. Because of the device's brilliant design and relative ease of use, it has dominated the portable mp3 market and become ubiquitous in many places, especially amongst young people. Apple, at the same time it created the iPOD, also created the itunes music store where users could download legal copies of music. Although there had been attempts before to make downloading music legal, they had largely failed. What made Apple's operation so successful is that it was combined with the launch of the ipod: so thousands of users were using itunes software anyway, as it was necessary to operate the ipod, and the music store was only a click away in the itunes software.
Apple has been innovative in making downloading music legal by partnering and offering many special incentives through its store. Many well known artists have released 'i-tunes only' singles that are available for download only at the i-tunes music store. It seems, after the years of rampant music piracy, a shift is being made back to making downloading music legal, thanks in large part to the success of the ipod and the itunes music store.