Compound interest, the friendly version
The same force that makes credit-card debt sticky is the one that quietly builds wealth. The only difference is which side of it you're standing on.
A snowball, not a ruler
Simple interest grows in a straight line: 5% of $1,000 is $50 a year, every year. Compound interest grows in a curve, because each year's interest joins the pile and earns interest too. Year one you earn $50. But you're now earning 5% on $1,050, then on $1,102.50, and the gap widens every year. Early on it's boring. Later it's the whole story.
Why time beats timing
Because the curve steepens over time, the most valuable ingredient isn't a clever pick or a big deposit — it's years. Money you save in your twenties has decades to compound; the same amount saved later simply has less runway. That's the real reason "start early" is the most repeated advice in finance: you're not buying returns, you're buying time.
The flip side is the lesson from earlier in this guide: on a credit card, that same curve is compounding against you. Clear the debt, then put the snowball on your side.