Big names Robbie Williams is the one person guaranteed to sell millions of records. Blue and Liberty X are among those popular with young fans while David Gray and Dido appeal to a more mature market.

Rising stars Young male trio Busted have successfully married a rock image with pop songs and success - while the market is flooded with TV talent show hopefuls.

Who listens? The biggest artists appeal to everyone - but impressionable fans aged eight to 16 are the main target for record companies.

Evolution Pop started when the first chart was published 50 years ago, but took off when the Beatles arrived. Their achievements remain unmatched and screaming teenage fans have been the most powerful force in British pop ever since.

To stay relevant, pop has borrowed the best bits from other styles - from the glam rock and disco of the 1970s to club culture in the 1990s. Pin-up groups have always had huge appeal but Take That and the Spice Girls perfected the formula. And in the new millennium, TV talent shows like Pop Idol brought the star production line into the open. Pop accounts for 50% of single sales and 30% of albums.