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. Laboratories analyze blood samples to measure components like red blood cells, white blood cells, and platelets. They can also test for specific substances, such as glucose or cholesterol, to assess a person's health. The results help healthcare providers make informed decisions about treatment and care.