What are T-bills and T-bonds? 

Treasury bills (T-bills) and treasury bonds (T-bonds) are investments issued by the US government and are often collectively referred to as treasuries. By investing in treasuries you essentially loan the US government money in return for a fixed rate of interest paid to you, either every six months or when the investment’s agreement period concludes. 

Treasury bills are considered short-term investments and reach maturity within a year when the loan amount is then paid back to you. Treasury bonds are considered long-term investments, reaching maturity over 30 years.