Oxygen therapy for COPD is more than 60-70 years old. In this long period, a vast amount of knowledge has been gained of the advantages and dangers of the same. Newer ideas, experiments, and their evaluation is part of any scientific endeavor and oxygen therapy is the newest technique that aims at giving air enriched with oxygen to breath. One type is exertion induced COPD. Oxygen enriched air is to be breathed in only during the exercise. This is seen to increase endurance and efficacy of exercise. This helps patients to maintain or even improve their physical fitness improving the COPD also. The real need of long-term oxygen therapy is for those suffering chronic oxygen deficiency in their blood. The condition is called chronic hypoxemia or hypoxia. Long-term oxygen treatment will improve the quality of life and also lifespan. One suffers less shortness of breath. It slows or even prevents Right Sided Heart Failure, which is the normal consequence of COPD. Oxygen therapy for chronic COPD is resorted to after normal medical treatments for COPD have ceased to benefit the patient. There are different ways to introduce the oxygen. Oxygen concentrators, liquid oxygen devices and the more conventional oxygen cylinders can all be used to augment the oxygen into the air that is breathed.