During the course of every day, each bank executes a large number of transactions, such as payroll, retail and business purchases, credit card payments, etc. Some involve cash (or its equivalent) coming into the bank and others of cash going out. Banks do not have a reliable way of predicting what or how much those transactions will be. At the end of each day banks must reconcile their positions. The bank that finds itself with a surplus of cash would miss out earning interest on the cash, even if it's for only one night. Other banks may find that they had more money going out than coming in, and the bank must borrow cash to cover the shortfall. To meet its liquidity obligations, the bank with the shortfall would borrow from a bank with a surplus in the interbank lending market. Depending on the bank's assessment of the type of shortfall and costs, the bank may take out an overnight loan, the interest rate of which is based on the cash rate, which is set by the Reserve Bank (RBA) every month (currently 0.25%); or else take out a "short duration loan", known as "prime bank paper", for a term of between one and six months and whose interest rate is called the "bank bill swap rate" (BBSW), which is set by the commercial banks.