The four individuals who make up the Beatles, one of the most influential and commercially successful bands of all time --  George Harrison, John Lennon, Paul McCartney and Ringo Starr -- can be considered the four cornerstones of rock 'n' roll music over the past five decades.

The Beatles were active for only 10 years, but they managed to leave a massive footprint that still looms large over popular music today.

With more than 177 million records sold in the U.S. alone over the past 50 years and 20 No. 1 hits achieved during their brief decade together, Beatlemania still shows no signs of slowing down.

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