From ArticleWorld

Serology is the study of the antibody-antigen interaction in the blood. Antibodies are proteins produced by the immune system. Each type of antibody is unique and their purpose is to protect the body against foreign substances which have entered the body and threaten it in some way such as chemicals or viruses. These foreign substances are called antigens which manifest themselves as chemical structures attached to the red blood cells.

Medical serology

Blood tests are undertaken to distinguish blood type or when an infection is suspected. Antibodies are present in the blood due to the fact that people have allergies or have or have had a disease such as TB, smallpox or hepatitis. As each antibody is unique, an examination is able to disclose the type of illness invading the system. All blood groups can be classified by the antigen in their red blood cells and the antibodies in the serum of the blood.

Forensic serology

A forensic serologist is a specific field of criminal investigation dedicated to determining the type and characteristic of blood and blood spatters and patterns. In the days before the use of DNA, blood testing was considered the most important tool in forensics and was used to establish victim/perpetrator interactions and to validate alibis. If serologists are able to distinguish between the antibodies in the blood of identical twins at a time when even their DNA profile is the same, then it remains a vital field even today.