Petrol-pump prices do not change every time the oil price changes, and holiday prices and standard hotel rates are fixed for months. Sticky prices are slow to change in response to changes in supply or demand. As a result there is, at least temporarily, disequilibrium in the market. The causes of stickiness include menu costs, inadequate information, consumers’ dislike of frequent price changes and long-term contracts with fixed prices. Prices change only when the cost of leaving them unchanged exceeds the expense of adjusting them. In financial markets, prices move all the time because the cost of quoting the wrong price can be huge. In other industries, the penalty may be much less severe. Small disequilibria in, say, the pricing of hotel rooms will not make much difference. So hotel prices are often sticky.