A thermostat symbol is an internationally-recognized sign used to indicate the presence of a thermostat or temperature regulator. It is widely used in both residential and commercial properties to signify control over the indoor environment, such as through heating, cooling, and air conditioning systems. The standard symbol includes a central circle surrounding a two-angled curving line, which can be seen in both analog and digital forms. Thermostat symbols have been adopted by many countries worldwide to help ensure their controlled environments operate efficiently and safely.