<P> All albums included on this list have their available claimed figures supported by at least 30% in certified copies . The percentage amount of certified sales needed increases the newer the album is, so albums released before 1975 are only expected to have their claimed figures supported by at least 30% in certified copies . However, newer albums, such as 21 and Come Away with Me, are expected to have their claimed figures supported by at least 70% in certified copies . Certified copies are sourced from available online databases of local music industry associations . This is the reason why albums that would otherwise make the list, such as The Sound of Music, In - A-Gadda - Da - Vida, Parallel Lines, Spirits Having Flown, Private Dancer, Janet, Believe, Bolo Ta Ra Ra..., Human Clay, Laundry Service and Back to Black, have not been included . </P> <P> As a result of the methodology that the American and Canadian certification - awarding bodies (the RIAA and Music Canada respectively) use, each disc in a multi-disc set is counted as one unit toward certification, leading to many double albums on the list--such as Pink Floyd's The Wall and the Beatles' The Beatles--being certified with a number double the number of copies sold there . Such albums have the certifications for the number of copies (not discs) shipped indicated . Conversely, the American certification level for double albums that fit onto one compact disc, such as the Saturday Night Fever soundtrack reflect the actual number of copies sold . </P> <P> Michael Jackson's Thriller, estimated to have sold 66 million copies worldwide, is the best - selling album . Although sales estimates for Thriller have been as high as 120 million copies, these sales figures are unreliable . Jackson also currently has the highest number of albums on the list with five, while The Beatles, Madonna and Celine Dion each have three . </P> <P> Groupings are based on different sales benchmarks, the highest being for claims of at least 40 million copies, and the lowest being for claims of 20--29 million copies . Albums are listed in order of number of copies sold and thereafter by the artist's first name . Markets' order within the table is based on the number of compact discs sold in each market, largest market at the top and smallest at the bottom . </P>

Who has the biggest selling album of all time