Principal vs. interest.

In plain English

Only principal payments reduce what you owe. Interest is the rent on the outstanding balance, recalculated as the balance falls. This is why "I've paid $30,000 on my loan" and "my balance fell $30,000" are very different sentences, especially early in a mortgage or on minimum-payment credit cards.

01Why it matters

It's the difference between money that shrinks your debt and money that just rents it, which is most of the early payments on a long loan.

02The math, step by step

Five years into the $380,000 mortgage at 7%, you've paid about $151,700 in payments. The balance has dropped by only about $22,300. The other $129,400 was interest. Plain numbers, no judgment, but you should know which is which.

Illustrative example. The amounts here are hypothetical, chosen to show how the math works, not real quoted rates or figures.

03What this is NOT