Cheryl,
They are prodcuts / instruments designed by Banks whereby they have combined a guaranteed deposit and juiced it up where by your return can increased if a certain thing happen
For example, last time they offered me a product whereby the principal is guaranteed and the retun is at minimal 2% (note the 3 mnth deposit rate at that time was 2.8%)
But depending on the movement of the EUR/USD the return can go up to 6%.
Now in my case I got 4.5%. But most of the time I only buy the once where the money is used for interbank lending rather than betting on movements of a certain underlying (FX, or stocks or index)
Bear in mind I am based in China!
There are other products where they offer much higher return but there is more risk (http://www.economist.com/node/18118975).
I believe banks in US / Europe offer structured products as well whereby this is packaged with the stock exchange or certain stocks do certain movements.