The primary purpose of a thermostat is to regulate and maintain a desired temperature within a specific environment, typically a building or home. Thermostats function by monitoring internal temperatures and controlling heating, ventilation, and air conditioning (HVAC) systems to ensure comfort. When the temperature deviates from the preset range, the thermostat triggers the system to either heat or cool the space until the desired temperature is achieved. Modern thermostats can be programmable or smart, allowing users to set schedules or adjust settings remotely via smartphones, enhancing energy efficiency and providing convenience in temperature management.