Every year Forbes magazine compiles a list of the world's richest people, the only pre-requisite being that they're net worth is more than US$1 billion. This year's list contained 793 billionaires throughout the world, up from three year's ago when the list had only 476.

But what does it take to compile a list this thorough and so global? An incredible amount of luck it would seem. Forbes explain it in this article as a behind-the-scenes view of their journalistic endeavours. For every billionaire who agrees to be interviewed four others reject the offer.

Not surprising though, I think if I were a billionaire I'd prefer to be fairly closed about my private life and business dealings too. Still, thanks to the Forbes team we're all allowed a little window into some of these amazing people's lives.