Treasury Inflation-Protected Securities (or TIPS) are the inflation-indexed bonds issued by the U.S. Treasury. The principal is adjusted to the Consumer Price Index (CPI), the commonly used measure of inflation. When the CPI rises, the principal adjusts upward. If the index falls, the principal adjusts downwards. The coupon rate is constant, but generates a different amount of interest when multiplied by the inflation-adjusted principal, thus protecting the holder against the official inflation rate (as asserted by the CPI). TIPS are currently offered in 5-year, 10-year and 30-year maturities.