Combustible gas refers to any gas that can ignite and burn when mixed with air. Common examples include natural gas, propane, and butane. These gases are often used as fuels for heating, cooking, and powering vehicles due to their ability to produce energy when combusted. When combustible gases are released into the atmosphere, they can pose safety risks, such as explosions or fires, if not handled properly. It is essential to have proper ventilation and detection systems, like gas detectors, to monitor for leaks and ensure safe usage in homes and industrial settings.