In 1990 hedge funds managed some $39 billion of assets. By late 2006 that figure had grown to $1.3 trillion. That is a staggering increase. Equally staggering is the amount of money successful hedge fund managers earn. In 2006 the top 25 hedge fund managers were paid $14 billion between them, with the top three earning over $1 billion each. Most people have heard the term 'hedge fund' but few are clear about what exactly a hedge fund is or what it does. This guide aims to put them in the picture with the clarity and lively prose that "The Economist" is famous for. It provides a succinct survey of the industry for all those who think they should know about hedge funds, but do not. It is aimed at all those who might want or have to deal with a hedge fund: private investors, trustees of a pension fund, directors of a listed company, lawyers and accountants who may be interested in working in the industry. It is also aimed at those who happily criticize hedge funds without really knowing what they do.