A complete blood count (CBC) test measures levels of red blood cells, white blood cells, and platelets to assess overall health and detect various medical conditions such as infections, anemia, and blood cancers. The test is performed by taking a blood sample from a vein and the results can indicate various health issues based on the levels of different blood components. Factors like diet, medication, and physical activity can influence cytometer results, and further details can be found at the provided link.