Mortgages

What Is a Mortgage?

A mortgage is a long-term loan used to buy a home, where the property itself acts as collateral — meaning the lender can take possession of the home through foreclosure if the borrower stops making payments. Because homes are expensive, mortgages typically stretch over 15 to 30 years, letting buyers spread an enormous purchase into monthly payments they can realistically afford.

Very few people can pay for a home in cash, so understanding how mortgages work is one of the most practical pieces of financial knowledge an adult can have.

The Building Blocks of a Mortgage

Every mortgage is built from a few core pieces:

• Principal — the amount of money actually borrowed to buy the home
• Interest rate — the percentage charged by the lender for borrowing the money, expressed as an annual rate
• Down payment — money the buyer pays upfront, which reduces how much needs to be borrowed
• Term — the length of time over which the loan is repaid, commonly 15 or 30 years

A larger down payment reduces the principal borrowed, which in turn reduces the total interest paid over the life of the loan — this is the same underlying idea covered in interest basics and compound interest, just applied to a very large loan.

Amortization: How Payments Are Split

Mortgages are typically repaid through amortization, meaning each monthly payment is a fixed amount that covers both principal and interest, recalculated every period based on the remaining balance.

Early in the loan, the outstanding balance is at its highest, so most of each payment goes toward interest, with only a small portion reducing the principal. As the years pass and the balance shrinks, the split gradually flips — later payments put more money toward principal and less toward interest. This is why paying extra toward principal early in a mortgage can save a substantial amount of interest over time.

Fixed-Rate vs Adjustable-Rate Mortgages

Two common mortgage structures work very differently:

Type	How it works
Fixed-rate	The interest rate stays the same for the entire term, so monthly payments never change
Adjustable-rate (ARM)	The interest rate starts fixed for a set period, then adjusts periodically based on market conditions

Fixed-rate mortgages offer predictability, which many buyers value for long-term budgeting. Adjustable-rate mortgages often start with a lower rate but carry the risk that payments could rise later if interest rates increase.

Beyond Principal and Interest

A monthly mortgage payment often includes more than just principal and interest:

• Property taxes — charged by local governments, often collected monthly and held in escrow
• Homeowners insurance — protects against damage or loss, usually required by the lender
• Private mortgage insurance (PMI) — often required when the down payment is below a certain threshold (commonly 20 percent), protecting the lender if the borrower defaults

Together these are sometimes bundled into a single monthly payment, so the true cost of homeownership is usually higher than the "principal and interest" figure alone suggests.

Worked Example — The Effect of a Down Payment

Imagine two buyers purchasing identical $200,000 homes. Buyer A puts down 5 percent ($10,000) and borrows $190,000. Buyer B puts down 20 percent ($40,000) and borrows $160,000. At the same interest rate, Buyer B borrows less principal, pays less interest over the life of the loan, and — because the down payment clears the common 20 percent threshold — likely avoids paying PMI altogether. The larger upfront payment costs more today but saves money for years afterward.

Mortgages and Bigger Financial Decisions

A mortgage is often the largest debt a person ever takes on, which makes it closely tied to ideas like good debt vs bad debt and renting vs buying. Lenders also weigh a borrower's credit score heavily when setting mortgage terms — a stronger credit history typically unlocks a lower interest rate, which can save tens of thousands of dollars over a 30-year term.

Key Words

• Mortgage — a long-term loan used to buy property, secured by the property itself
• Principal — the amount of money borrowed, before interest
• Amortization — repaying a loan through fixed payments that gradually shift from mostly interest to mostly principal
• PMI (private mortgage insurance) — insurance often required when a down payment is small, protecting the lender