Drawing blood is the process of extracting blood from a person's veins for diagnostic or therapeutic purposes. There are several other terms used to describe the same process. Phlebotomy is another term used to describe drawing blood. Venipuncture is a medical procedure used to draw blood from veins using a needle. Bloodletting is the practice of removing blood from a patient's body as a treatment for certain medical conditions. Needle biopsy is a procedure where a needle is inserted into a tissue to collect a small sample of cells for testing. Hematocrit is a diagnostic test which measures the percentage volume of red blood cells in the blood. Overall, drawing blood is an essential process for diagnosing and treating a wide range of medical conditions.