Money basics

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

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

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APR vs AER: What's the Difference?
APR is what borrowing costs. AER is what saving earns. Both are annual percentages, both are regulated, and they measure opposite things.
Updated 25 August 2026 · 2 min read
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What Is APR? Representative APR Explained
APR is the yearly cost of borrowing including compulsory charges. In the UK, most advertised rates are 'representative' — which means fewer than half of applicants may get them.
Updated 25 August 2026 · 3 min read