Pulse oximetry is a non-invasive method used to measure the oxygen saturation level in a person's blood. It works by attaching a small device, called a pulse oximeter, to a fingertip or earlobe. The device uses light to assess how much oxygen is being carried by red blood cells, providing a quick and painless reading. This technology is commonly used in hospitals, clinics, and even at home to monitor patients with respiratory or cardiac conditions. Normal oxygen saturation levels typically range from 95% to 100%. If levels fall below this range, it may indicate a need for medical attention.