A blood sample is a small amount of blood taken from a person for medical testing. This sample can be collected through a needle inserted into a vein, usually in the arm, or through a finger prick. Blood samples are essential for diagnosing various health conditions, monitoring diseases, and checking overall health. Once collected, the blood sample is sent to a laboratory for analysis. Tests can measure different components, such as red blood cells, white blood cells, platelets, and plasma. Results from these tests help healthcare providers make informed decisions about a patient's treatment and care.