Human serum refers to blood serum derived from people. It is used in a variety of medical and research applications. Human serum is generally collected from donated blood from voluntary donors. Blood is collected under sterile conditions, then centrifuged to separate the cells from the blood plasma. The plasma is then processed to obtain serum. Human serum is used in many immunology studies to understand the body's immune response and defense mechanisms. It can be used to detect the presence of specific antibodies in serological tests, such as those for infectious diseases, or to assess immune responses in various medical conditions.