A Bunsen burner is a device used in chemistry for heating. It is named after Robert Wilhelm Bunsen, who perfected its design.
The device safely burns a continuous stream of gas without the risk that the flame will travel back down the tube to the gas supply. It is most common for the burner to run on natural gas, which is a combination of propane and butane. Natural gas is basically methane with only small amounts of propane and butane.
The burner has a weighted base, where the gas supply tube plugs into, and a vertical tube rising from it. The gas flows from the connection to the gas supply, and between the base and the tube. The stream of gas then passes the hole in the side of the tube. It then mixes with air if the hole is open. At the top of the tube, the gas is ignited, and it then burns.
If the collar at the bottom of the tube is adjusted so more air can mix with the gas before combustion, the flame will burn hotter(appearing blue) as a result. However, if the hole is closed, the gas will mix with oxygen in the atmosphere at the point of combustion, and so it will burn less efficiently, producing a cooler flame (appearing yellow). By adjusting this, and the in-flow of gas, the heat of the flame can be controlled.