Gas burners work using a mixture of natural gas and oxygen that is ignited by a pilot light, or, in newer stoves, an electric spark igniter. The height of the flame is determined by the amount of gas fed into the burner. An alternative fuel source is propane.
The natural gas is delivered via a series of underground pipes connected to the city gas supply. The gas is pressurized. When the stove is turned on, the gas flows into the stove's pipes and is mixed with air on its way to the burner. The air not only makes it easier to ignite the gas, but it allows the user to control the flame better.
The piping in the stove includes a smaller branch that leads to the pilot light or the electric spark igniter. A small amount of gas is lit in this smaller pipe, then the flame travels back to the main pipe to light the main gas source. The flame travels to the burner and flows through the tiny holes in the burner's base. Turning the stove controls adjusts the height and strength of the flame.
The color of the flame determines the amount of oxygen present. A properly mixed flame is blue, with sometimes a hint of yellow when the flame is set at a lower temperature. If the flame is predominantly yellow or orange, too much oxygen is present and the mixture needs adjustment.