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The business of being Lady Gaga

21 February 2011 Last updated at 12:03 GMT

Lady Gaga's new track Born This Way is officially the fastest selling single ever on iTunes.

But the singer is also a savvy business woman. With an army of more than eight million Twitter followers, she understands digital media better than most and has arguably taken product placement and marketing tie-ups to a new level.

Her latest venture is with Mac to promote a range of cosmetics which helps fund Aids research. Michelle Fleury in New York went to meet her.