Treasury Bill - T-Bill

What Does Treasury Bill - T-Bill Mean?
A short-term debt obligation backed by the U.S. government with a maturity of less than one year. T-bills are sold in denominations of $1,000 up to a maximum purchase of $5 million and commonly have maturities of one month (four weeks), three months (13 weeks) or six months (26 weeks).

T-bills are issued through a competitive bidding process at a discount from par, which means that rather than paying fixed interest payments like conventional bonds, the appreciation of the bond provides the return to the holder.

Investopedia explains Treasury Bill - T-Bill
For example, let's say you buy a 13-week T-bill priced at $9,800. Essentially, the U.S. government (and its nearly bulletproof credit rating) writes you an IOU for $10,000 that it agrees to pay back in three months. You will not receive regular payments as you would with a coupon bond, for example. Instead, the appreciation - and, therefore, the value to you - comes from the difference between the discounted value you originally paid and the amount you receive back ($10,000). In this case, the T-bill pays a 2.04% interest rate ($200/$9,800 = 2.04%) over a three-month period.