The Giving Pledge is the brainchild of billionaire businessmen Bill Gates and Warren Buffett. The two of them have teamed up to ask the world's wealthiest people to donate at least 50% of their fortunes to charities. They believe that the richest people in the world can eradicate many of the world's problems through philanthropy. The pledge is not a binding contract but more of a "moral commitment". Individuals are free to donate money to whatever cause they would like. So, far about 40 billionaires have accepted the giving pledge challenge. That's not a large number when you consider that there are nearly 1,000 billionaires in the world, according to Forbes.