A machine used to measure temperature is called a "thermometer." Thermometers come in various types, including liquid-in-glass, digital, and infrared. Liquid-in-glass thermometers use the expansion of liquids, like mercury or colored alcohol, to provide temperature readings. Digital thermometers, often used in medical settings, utilize electronic sensors to give quick and accurate temperature measurements. Infrared thermometers, which measure the temperature of surfaces from a distance, are commonly used in various industries. Thermometers are essential tools in medicine, meteorology, cooking, and numerous scientific applications, providing critical data in many contexts.