A front-end load is a commission or charge when you initially buy shares in the fund. Front-load fees are usually around 5% of the amount you invest in the fund. These are identified as Class A shares.
A back-end load is a fee that you pay upon selling your shares in a mutual fund. You are charged this fee when you sell the shares within a time frame of five to 10 years of buying into the fund. The amount of the fee usually goes down the longer you hold the shares. The fee is the highest for the first year you hold the shares. These are called Class B shares.