Radon (222Rn) is an element with an atomic number of 86 and a half-life of 3.82 days. It is a noble gas and exhibits behavior similar to that of an ideal gas. Radon concentrations in the soil, water, and atmosphere vary in response to crustal movement. This is because Radon is a radioactive gas that is released from cracks and cavities in the Earth's crust as it is strained before an earthquake. Radon concentrations can be abnormally high along active faults, which may be paths of least resistance for the outgassing process. In this paper, different instances of anomalies in Radon concentration as an Earthquake Precursor are discussed along with some discussion on the Radon production, measurement and transport methods.