The primary purpose of a thermometer is to measure temperature. Thermometers come in various types, including mercury, digital, and infrared, each designed to provide accurate temperature readings for different applications. They are widely used in various fields such as meteorology, medicine, and cooking. In healthcare, for example, thermometers help assess a person's fever, guiding medical decisions. In meteorology, they offer essential data for weather predictions. The ability to measure temperature accurately is crucial in scientific experiments, industrial processes, and everyday activities, making thermometers vital tools for monitoring thermal conditions.