From wikipedia
http://en.wikipedia.org/wiki/Hedge_fund

A hedge fund is an investment fund open to a limited range of investors that undertakes a wider range of investment and trading activities than long-only investment funds, and that, in general, pays a performance fee to its investment manager. Every hedge fund has its own investment strategy that determines the type of investments and the methods of investment it undertakes. Hedge funds, as a class, invest in a broad range of investments including shares, debt and commodities.