A Complete Blood Count (CBC) is one of the most commonly ordered blood tests, providing important information about the cells in your blood. The test measures red blood cells (which carry oxygen), white blood cells (which fight infection), hemoglobin (the oxygen-carrying protein), hematocrit (percentage of blood volume that is red cells), and platelets (which help clotting). Results help doctors screen for various conditions including infections, anemia, clotting disorders, and certain cancers. A CBC is often part of routine health checkups and is used to monitor overall health, diagnose conditions, and track treatment effectiveness. The test requires a simple blood draw.