An oven thermometer is a device that measures the temperature inside an oven. It is useful for checking the accuracy of the oven's thermostat, ensuring even heating, and preventing overcooking or undercooking of food. 

A digital fridge freezer thermometer can be useful for monitoring the performance and efficiency of a fridge or freezer, as well as for complying with food safety regulations and standards.

Handheld digital thermometers are widely used in various fields, such as medicine, food safety, industrial applications, and environmental monitoring.

The thermometer converts the radiation into an electrical signal, which is displayed as a temperature reading on a screen. Infrared digital thermometers are useful for measuring temperatures in situations where contact is undesirable or impractical, such as in industrial, medical, or food safety applications.

Digital thermometers are more accurate, faster, and easier to use than traditional thermometers that rely on mercury or alcohol. Digital thermometers can be used for various purposes, such as measuring food temperature, room temperature, etc.