To get a free copy of the Infectious Generosity book, visit ted.com/generosity. Bill Gates, the founder of Microsoft and the co-chair of the Bill & Melinda Gates Foundation, is one of the top 10 richest people in the world. But since 2008, he has traded his day-to-day role with Microsoft to focus full-time on his foundation's work to expand opportunity around the world. Chris interviews Bill about his philanthropy philosophy and digs into the opportunities and challenges that face one of the largest private charitable foundations in the world. The two also discuss The Giving Pledge, the movement Bill co-founded with Warren Buffet, which encourages wealthy individuals to commit the majority of their wealth to charitable causes within their lifetimes. Chris and Bill examine the importance of solving the world’s most pressing problems efficiently, talk about why meaningful change requires scale and compare notes on how to best encourage collective excitement about giving back.