1. Digital Thermometer: These thermometers use a sensor to measure temperature and display the reading digitally on a screen. They are often used for taking body temperature, but can also be used to measure the temperature of objects or liquids.

2. Mercury Thermometer: These thermometers use a glass tube filled with mercury, which expands or contracts with changes in temperature. The level of mercury in the tube is then used to determine the temperature. Mercury thermometers are less common now due to safety concerns.

3. Infrared Thermometer: These thermometers measure the temperature of an object by detecting the infrared radiation it emits. They are often used for measuring surface temperatures of objects, such as food or engines. They are also sometimes used for taking body temperature without contact.