Back in the days of cassette tapes in breakable plastic cases, the music industry started releasing background-only versions of their artists' hits. For the most part, it was a supply-and-demand response to the karaoke culture. But in Christian book stores across the country, these tracks were primarily used for performance purposes, including Sunday morning services, church events, youth activities, weddings and other ceremonies. Called "Background tracks," "Accompaniment Tracks" or "Performance Tracks," they followed industry formats from cassette to CD, but came to a screeching halt in the digital age. While the tracks were available online for physical purchase, it was more difficult to buy or download the songs individually. In 2005, Word Music became the first Christian label to distribute performance tracks, via their Studio Series, digitally. The music on these (and other) albums usually follows a semi-standard format that includes a demo track (often the artist's original album version) as well as alternate editions in high, medium and low keys, with or without background vocals. The instrumental backgrounds are usually the same as in the original chart-toppers; the only difference is, you sing the hits.