Pulse oximetry is a non-invasive technology that measures the oxygen saturation level in a person's blood. It works by passing light through a thin part of the body, usually a fingertip or earlobe, using a small sensor device called a pulse oximeter. The device detects changes in light absorption caused by oxygenated and deoxygenated blood, providing real-time readings of blood oxygen levels and pulse rate. Pulse oximetry is widely used in healthcare settings to monitor patients' respiratory status, especially during surgery, in intensive care, or for those with respiratory conditions.