Just who is the richest person on Earth? Forbes launched the Forbes 2013 Billionaires List, which takes measure of the worlds wealthiest people. Forbes reported that for the 27th year of its publication, the list grew to 1,426 names, totaling $5.4 trillion, up from $4.6 trillion last year. The US led the list with 442 billionaires.
Learn more about the world's 20 richest people -- including three members of the Walmart founder's family, two Internet giants, and the founder of the world's largest software company.