MQ2 Gas sensor is a Metal Oxide Semiconductor (MOS) type Gas Sensor mainly used to detect gases like Methane, Butane, LPG, Smoke, etc. It is also known as Chemiresistors as the gas detection is based on the change of resistance of the sensing material when the Gas comes in to contact. If you want to measure a different type of Gas you can check these Gas Sensors.
MQ2 Gas sensor module works on 5V DC and uses around 800mW. It can detect LPG, Smoke, Alcohol, Propane, Hydrogen, Methane and Carbon Monoxide concentrations in a range of 200 to 10000 ppm
To use the MQ2 gas sensor module, you need to power the device with 5V supply and the Power LED will start to glow. You should give it some preheating time before start reading the output. While measuring the gas present, the Output LED will glow in a specific concentration of the gas. You can change it by using the potentiometer. Else you can also use the Analog Output to see how your program reacts to different concentration of gases present.