CPAP, or Continuous Positive Airway Pressure, is a medical device commonly used to treat obstructive sleep apnea. It works by delivering a steady stream of air through a mask that keeps the airway open during sleep, preventing interruptions in breathing. The use of a CPAP machine can improve sleep quality and reduce daytime fatigue for individuals with sleep apnea. Regular use can also lower the risk of related health issues, such as heart disease and high blood pressure, making it an important tool for managing this condition.