Treasury bills are short-term promissory notes issued by the government of India to finance its short-term borrowing needs. There are two types of treasury bills - ordinary bills which are freely tradable, and ad-hoc bills which are non-tradable and issued only to the RBI. Treasury bills are issued in 91-day, 182-day and 364-day maturities through weekly and fortnightly auctions. While treasury bills offer safety and liquidity, their yields tend to be low making them less attractive compared to other government securities.