Why is a thermometer put under a tongue?

A thermometer is placed under the tongue to measure oral body temperature, as this location provides a reliable and accurate reading of core body temperature. The area under the tongue is well vascularized, allowing for quick temperature changes to be registered. This method is commonly used because it is easy for individuals to perform themselves and typically yields consistent results. Additionally, it is one of the most practical sites for temperature measurement in both clinical and home settings.