Never before has one album's sales been the subject of so much conjecture. Depending on what you read, and ultimately who you believe, Thriller has racked up worldwide sales of anything between 50 million and well in excess of 100 million. Here at Guinness World Records, we confirmed Thriller as the planet's best-selling album with more than 65 million units shifted. Put another way, that's enough copies for the combined populations of the UK (63,742,977) and Estonia (1,257,921) in July 2014 - and then some.
What we know for certain is that the "King of Pop"'s sixth studio effort has been smashing records for fun since it emerged from the appropriately named Epic Records back in November 1982. Among its most notable achievements are seven trophies at the 1984 Grammy Awards (a single-ceremony feat surpassed only by Santana's Supernatural in 2000), seven US Top 10 singles (subsequently equalled by Bruce Springsteen and Janet Jackson from one album) and Recording Industry Association of America-certified shipments of 29 million units, tying Their Greatest Hits (1971-1975) by the Eagles as the most successful album released in the US.
After selling 32 million copies in 1983 alone, Thriller was confirmed as the world's biggest seller in February 1984, when it eclipsed The Dark Side of the Moon, Pink Floyd's 1973 classic.
"Ever since I was a little boy, I had dreamed of creating the biggest-selling record of all time," explained Michael in his 1988 autobiography Moonwalk. "Remember, I grew up knowing the industry, understanding goals, and being told what was and was not possible. I wanted to do something special."
But for all his success with Thriller, 1984 was a bittersweet year for the 25-year-old Jackson. While filming a commercial for Pepsi with his brothers, sparks from on-set pyrotechnics set his hair alight, resulting in second-degree burns to his head and face and an addiction to painkillers that many have attributed to his premature death in 2009. With talk shows and column inches mercilessly focusing on his unfamiliar physical appearance rather than his talents as a singer, dancer and entertainer, not to mention the creator of the world's best-selling album, for some Jackson's music had become of secondary importance to his troubled personal life.      
Back in the spring of 1982, things appeared to be altogether happier for Michael. Basking in the critical and commercial success of his 1979 album Off the Wall, he started work on Thriller with producer Quincy Jones and a reported budget of $750,000 at Westlake Recording Studios in Los Angeles. Ex-Beatle Paul McCartney was brought in to record his contribution to the surprising first single, "The Girl is Mine", and over the course of six months the album was moulded into the critically acclaimed masterpiece we know and love today.
Nine tracks made the final cut, including four written and co-produced by Jackson himself - set opener "Wanna be Startin' Somethin'", "The Girl is Mine", "Beat It" (featuring Eddie Van Halen) and "Billie Jean" - and arguably the album's most outstanding song, "Thriller", written by Cleethorpes' Rod Temperton and complete with American actor Vincent Price's sinister monologue. The album version of "Thriller" clocked in at 5:57. When film director John Landis' (An American Werewolf in London) zombie-themed video was masterminded to accompany the single's release in November 1983, the track had morphed into a 14-minute horror epic that fans and MTV alike couldn't get enough of. It was a knockout blow from a collection that had also given us Jackson's much-imitated signature move, the Moonwalk, executed for the first time on 25 March 1983 on an NBC TV special in celebration of Motown's 25th anniversary, during a memorable performance of "Billie Jean".
Besides the record-setting numbers, the string of hits and visuals that turned the humble music video into an art form, arguably the greatest legacy left by Thriller is the impact Jackson's music had at MTV. Traditionally the domain of white rock acts, the fledgling TV channel added "Billie Jean" (at first reluctantly), "Beat It" and "Thriller" to its playlists and a whole generation of viewers became hooked on Jackson's epic videos and his killer dance moves. The likes of Kanye West, Chris Brown and Jay Z unquestionably have Michael (and persistent record label bosses) to thank for banishing racial prejudice among short-sighted TV execs and giving today's black artists a valuable platform on which to express themselves.
And the story doesn't end there. In 2008, an expanded version of the album, Thriller 25, was released for a whole new generation of devoted Jackson fans. In the same year, the original Thriller was one of just 25 recordings deemed "culturally significant" by America's Library of Congress, and shortly before that it found its way into the Grammy Hall of Fame. 
In 2009, the year the world said goodbye to one of popular music's true icons, Thriller sold 1.27 million copies in the US alone, proving beyond doubt that Jackson's music lives on in the hearts and minds of his adoring fans. There will never be another performer like Michael Jackson, and on a number of levels, there will surely never be another album like Thriller.