Money basics

The vocabulary: APR, APY, AER, interest, inflation and the rest.

Everything here is written for the United States. Terminology, protection limits and regulators differ between markets, so a guide from another country will not transfer cleanly.

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APR vs APY: What's the Difference?
APR is what borrowing costs. APY is what saving earns. The difference between them is compounding — and it works for you in one direction and against you in the other.
Updated August 25, 2026 · 3 min read
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What Is APR? The Real Cost of Borrowing, Explained
APR is the yearly cost of borrowing including certain fees, not just the interest rate. Here is what it covers, what it leaves out, and when it misleads.
Updated August 25, 2026 · 4 min read