Pulse oximetry is a non-invasive method used to measure the oxygen saturation level in a person's blood. It works by using a small device, called a pulse oximeter, which is typically clipped onto a fingertip or earlobe. The device emits light wavelengths that pass through the skin and measure how much oxygen is bound to hemoglobin, the protein in red blood cells that carries oxygen. This measurement is important for assessing respiratory function and can help detect conditions like hypoxia, where the body or a part of the body is deprived of adequate oxygen supply. Pulse oximetry is commonly used in hospitals, clinics, and even at home to monitor patients with respiratory issues or during anesthesia.