How to choose ... thermometers Yes, the plural is correct: you need more than one. What are they? Several types are used in the kitchen to check the temperature of equipment (fridges, ovens) and food. Why are they used? Because temperature gauges built into equipment have been known to be inaccurate, and you're likely to find out only when it's too late - when the roast burns to a crisp in 10 minutes, even though the oven temperature was set at 180 degrees Celsius, or when everything in your freezer melts although you have the setting at minus 10 degrees Celsius. It is possible to cook most dishes without the use of a thermometer, but unless you're making large, expensive roasts on a daily basis, it's wise to use one rather than rely on instinct when checking if it's cooked. Types: Fridge and freezer thermometers are essential - you should leave one of these permanently hanging from a rack in both areas and check them frequently. If you have an oven, leave one in there as well, because oven temperature gauges are frequently unreliable. For large cuts of meat, buy an 'instant-read' probe thermometer. It's inserted when the meat is out of the oven and gives you the internal temperature of a roast within seconds. It can't be left in the roast during cooking because the plastic parts will melt. Instant-read thermometers are useful and versatile because they can also be used for pastry and confectionary tasks such as checking the temperature of chocolate or custards. Another type of thermometer goes to very high temperatures (more than 200 degrees Celsius) and can be used for deep-fat frying, jellies, caramels and other sweets. What else? Thermometers should be checked occasionally for accuracy. An easy way to do this is to dip the probe in boiling water - if it reads 100 degrees Celsius (boiling point), it's fine. Very accurate and expensive electronic digital thermometers will instantly give you the surface temperature of whatever you point them at. These are great for some jobs (in and out of the kitchen), but not so good for cooking meat, where you need to check the internal temperature.