This is the common term for the Contingent Deferred Sales Charge, which applies to mutual fund B-shares. Many people think about this concept if they are standing outside of Curves. But for better details, see b-shares. "Load" is commission - think of it as a "weight" on your investment returns. "Back end" means that it is paid at the end of the holding period of your mutual fund - that is, it is paid when you sell the fund, as opposed to when you buy.