Pneumothorax has typical manifestations on a chest X-ray. Normally, the pulmonary markings on both sides are quite clear and visible. However, when a pneumothorax occurs, the part of the lung tissue with these markings tends to be compressed due to the accumulation of a large amount of gas in the surrounding pleural cavity, pushing the lung to contract towards the center. Around the periphery, these lung margins, which are outside the lung, meaning inside the pleural cavity, display the gas as very uniform and fine, without any markings. This is because it is pure gas, simply air, hence it is impossible for it to have markings. There is a particularly distinct demarcation line, a thin line, between this part of the pleural cavity and the lungs. Through these features, one can determine the presence of a pneumothorax.