The Red Blood Cell (RBC) count is a fundamental component of a complete blood count (CBC) that measures the number of red blood cells in a person’s bloodstream. Red blood cells, also known as erythrocytes, are responsible for transporting oxygen from the lungs to tissues throughout the body and carrying carbon dioxide back to the lungs for exhalation. A normal RBC count typically ranges between 4.5 to 6 million cells per microliter of blood. Abnormal RBC counts can indicate various medical conditions, such as anemia (a deficiency in red blood cells) or polycythemia (an excess of red blood cells). Monitoring RBC counts is crucial for assessing oxygen-carrying capacity and diagnosing and managing a wide range of blood disorders and overall health conditions.