An oxygen concentrator is a medical device that provides concentrated oxygen to individuals who have difficulty breathing. It works by taking in air from the environment, filtering out nitrogen, and delivering a higher concentration of oxygen to the user. This is especially helpful for patients with respiratory conditions like COPD or asthma. Oxygen concentrators can be stationary or portable, allowing users to receive oxygen therapy at home or on the go. They are typically powered by electricity and have adjustable flow rates to meet individual needs. Unlike oxygen tanks, they do not require refilling, making them a convenient option for long-term use.