指利息计算的基础是
本金加先前累积的利息，与
单利相对，后者指利息只以初始
本金为计算基础。“按年复利”(compounding annually)是指当年利息只在一年结束时一次性纳入下一年的
计息基础。例如，如果存入100英镑，年
利率为10%，那幺一年后可获得110英镑。如果按
单利方式计算，两年后可获得120英镑，三年后则是130英镑，而复利计算则将上年的利息亦纳入
计息基础，即两年后可得121英镑，三年后则是133.10英镑。相对于
单利方式，三年后额外的3.10英镑利息即是复利作用的结果。
参见Simple Interest(单利)。
The interest amount earned both on the original
principal and on the accumulated interest.
Compounding annually means that there is only one period each year in which interest is calculated. For example, if £100 is deposited with annually calculated interest at 10 percent, after one year there will be £110. Where
simple interest always calculates the rate from the initial amount invested (giving £120 after two years, £130 after three etc.),
compound interest calculates the 10 percent from the previous year's total (giving £121after two years and £133.10 after three). The extra £3.10 is the compound interest.
See also: Simple Interest
