HYIP stands for High Yield Investment Program. While a HYIP may sound enticing, you should be careful; many HYIPs are little more than thinly disguised ponzi schemes.

A ponzi scheme is a system by which investors are lured to invest in a program by promises of very high returns on the investment. Early investors are paid using the money that later investors invest in the scheme. Things go well until new investors stop joining the system and the money runs out.