Amortization is the process of paying off a loan through a series of fixed periodic payments, where each payment covers both interest (calculated on the remaining principal) and a portion of the principal. Early payments are interest-heavy; later payments are principal-heavy.
When a fully-amortizing loan is created, the lender calculates a single fixed monthly payment that, paid over the loan term, exactly pays off the principal and accumulated interest. The math: early in the loan, most of each payment is interest because the principal balance is high. As the principal shrinks, the interest portion of each payment shrinks, and more goes to principal. For a 30-year mortgage at 7% APR on $400,000, the monthly payment is roughly $2,661. In month 1, ~$2,333 is interest and only $328 is principal. By month 360 (year 30), nearly the entire payment is principal. The 'amortization schedule' shows this breakdown month-by-month. Understanding amortization is critical when deciding whether to make extra payments. Every extra dollar applied to principal reduces all future interest charges proportionally — front-loaded extra payments save dramatically more interest than the same dollars paid later. A single extra payment in year 1 of a 30-year mortgage can shave 6-12 months off the loan; the same payment in year 25 barely moves the date. The CFPB's Regulation Z (12 CFR Part 1026, https://www.consumerfinance.gov/rules-policy/regulations/1026/) governs amortization disclosure requirements for consumer loans, requiring lenders to provide a full payment schedule. The CFPB's mortgage loan estimate guide (https://www.consumerfinance.gov/owning-a-home/loan-estimate/) explains how amortization is disclosed on the Loan Estimate form before closing.
A loan where the fixed monthly payments fully pay off the principal + interest over the loan term. Mortgages, auto loans, and most personal loans are fully-amortizing. Interest-only loans (some HELOCs, some commercial loans) are NOT amortizing — the payments cover interest only, leaving the principal due at maturity.
Almost always yes when (a) you have no higher-interest debt to pay off first, (b) the loan has no prepayment penalty (most modern loans don't), and (c) your liquidity is adequate. Every dollar applied to principal saves the entire future interest stream that dollar would have generated. The earlier in the amortization schedule, the bigger the impact.