infrared thermometers use infrared energy to detect temperatures. since they are detecting actual energy levels, the physical thermometer does not need to actually touch the surface for an accurate temperature measurement. they don't even send out any information or infrared rays themselves, they merely detect them from a distance, sometimes miles away. some are used for weather forecasting and research and are able to tell the temperature of clouds at high altitudes. they are also used in many manufacturing processes that have temperature requirements and especially useful for monitoring products on a movable production line.