The Complete Blood Count (CBC) test is a blood test that measures various components of the blood, including red blood cells, white blood cells, and platelets. It is one of the most commonly ordered blood tests and is used to help diagnose a variety of conditions, including infections, anemia, and blood disorders. The test provides important information such as the number of red blood cells, which carry oxygen throughout the body, and the number and types of white blood cells, which are important for fighting infections. The CBC test can also measure hemoglobin levels, which is a protein in red blood cells that carries oxygen, and hematocrit levels, which measures the percentage of red blood cells in the total blood volume. The test is performed by taking a small sample of blood from a vein in the arm and analyzing it in a laboratory. The results are typically reported as numerical values and compared to reference ranges to determine if any values fall outside of the normal range. Depending on the results, further testing or treatment may be recommended.