A gas furnace is a heating system that uses natural gas or propane to generate heat for residential or commercial spaces. It works by igniting gas in a burner, which heats air that is then circulated through ducts by a blower. This process efficiently warms up rooms, making it a popular choice for many households. Gas furnaces are known for their effectiveness and cost-efficiency, especially in colder climates. They typically have a thermostat that allows users to set their desired temperature. Regular maintenance, such as checking the flue and changing filters, is essential for optimal performance and safety.