The music industry has always charted sales of singles and albums as a way of tracking the success of different types of music and creating an atmosphere of healthy competition amongst artists. To this day the goal of any artist is to have a number one record and to see their music become part of popular culture.
Since the launch of MP3s and other forms of digital music, the industry has begun to take the most popular music downloads into consideration when compiling music charts. In February 2005 digital sales were included for the first time in the US Billboard charts while the UK began charting downloads in September of the previous year. Initially digital downloads had their own specific chart, however by January 2005 digital tracks were outselling physical singles for the first time, so the most popular music downloads were incorporated into the regular charts.
Most websites selling digital music will have their own charts indicating what the most popular music downloads are amongst their users and many will divide these charts into sub categories. For example, websites for the electronic music market like Beatport and DJ Download will chart the most popular music downloads in every genre that they represent, from hip hop to techno, garage to electro. This way fans can find out, not just what the overall best selling track on the site is, but also what tracks are selling well within their particular genre.
Nowadays there is very little difference between the most popular music downloads and physical CD sales. Generally speaking if a track is doing well in one medium it is more than likely having similar success in the other. The only genres that may show discrepancies are those favoured by a slightly older demographic. For example, CD sales still tend to be bigger than downloads in genres like classical music, folk music and country and western. However, as the older generation begins to catch up with younger music buyers this trend will more than likely change.