One of the reasons for the iPod's early success, having been released three years after the very first digital audio player (namely the MPMan), was its seamless integration with the company's iTunes software, and the ecosystem built around it such as the iTunes Music Store, as well as a competitive price. As a result, Apple achieved a dominance in the MP3 player market as Sony's Walkman did with personal cassette players two decades earlier. The software between computer and player made it easy to transfer music over and synchronize it, tasks that were considered difficult on pre-iPod MP3 players like those from Rio and Creative.