Compound interest is interest earned on both the original principal and the interest already accumulated. The future value is A = P × (1 + r/n)^(n·t), where P is the principal, r the annual rate as a decimal, n the number of compounding periods per year and t the number of years. Total interest is simply A − P. A higher compounding frequency (daily vs annually) produces a slightly larger result because interest starts earning interest sooner.
The year-by-year table shows the balance at the end of each year and the interest credited that year, so you can see how growth accelerates over time. Everything is calculated locally in your browser; nothing about your money is uploaded.