The amortization period on a mortgage is the total length of time it will take you to pay off your mortgage. A fairly typical amortization period is 25 years, but it certainly can be shorter. In comparison, the term of a mortgage (which ranges from 6 months to 10 years) represents the length of time for which your mortgage agreement with a lender is valid.
Some people choose a longer amortization period because it lowers their mortgage payments. Simply put, the longer the amortization, the lower the mortgage payments. This can mean, for some, the difference between buying and not buying a home. Longer amortization periods do mean however, that the longer it takes you to pay back the mortgage principal to the lender, the more interest you will pay.