Oxygen saturation (O2 saturation or SpO2) measures the percentage of hemoglobin in blood carrying oxygen, normally 95-100% in healthy individuals. Healthcare providers monitor oxygen saturation using pulse oximeters, small devices clipped to fingers that measure blood oxygen levels non-invasively. Low oxygen saturation indicates respiratory problems requiring medical attention. During the COVID-19 pandemic, oxygen monitoring became more widely understood as respiratory symptoms required tracking. Emergency medical services routinely monitor patient oxygen levels. Understanding basic health metrics like oxygen saturation helps citizens communicate with healthcare providers and recognize when medical attention is needed.