IR stands for infrared, referring to the infrared rays which some thermometers use to measure. NCIT stands for no-contact infrared thermometer, which measures from a distance. These are also sometimes referred to as no-contact instead of no-touch. Not are IR thermometers are NCITs, but all NCITs use IR. For example, ear thermometers use IR, but they still require touch. Some industrial thermometers can use either a probe or IR depending on the user's needs.