Treasury bills, also known as T-bills, are short-term debt securities issued by the U.S. government with maturities ranging from a few days to 52 weeks. They are sold in denominations of $100, $1, 000, $10, 000, and $100, 000. The primary buyers of Treasury bills are large financial institutions, such as banks and mutual funds. The interest rate on Treasury bills is determined at auction and is usually lower than other types of debt securities. Treasury bills are considered one of the safest investments available and are often used by investors looking for a low-risk option.