A lighter spark is the ignition source for gas. The article discusses how a simple spark from a lighter is all it takes to ignite gas. This process is commonly used in various applications such as lighting a stove or starting a fire. The article emphasizes the importance of caution when dealing with gas and open flames to prevent any accidents. It also highlights the convenience and efficiency of using a lighter spark for igniting gas compared to other methods. Overall, the article underscores the significance of the role a lighter spark plays in igniting gas safely and effectively in everyday settings.