High School Musical is a 2006 American television film and the first installment in the High School Musical trilogy. Upon its release on January 20, 2006, it became the most successful film that Disney Channel Original Movie (DCOM) ever produced, with a television sequel High School Musical 2 released in 2007 and the feature film High School Musical 3: Senior Year released to theaters in October 2008. It is the first Disney Channel Original Movie to have a theatrical sequel. The film's soundtrack was the best-selling album in the United States for 2006. High School Musical was Disney Channel's most watched film that year with 7.7 million viewers in its premiere broadcast in the US, until August's premiere of The Cheetah Girls 2, which achieved 8.1 million viewers. In the UK, it received 789,000 viewers for its premiere (and 1.2 million viewers overall during the first week), making it the second most watched program for the Disney Channel (UK) of 2006.