Antibodies are proteins produced by the immune system in response to the presence of foreign substances, such as pathogens or toxins. These proteins bind specifically to their target antigens, marking them for destruction by other immune cells. Antibodies play a crucial role in the body's defense against infections and diseases, and are also used in various research and medical applications, such as diagnostic tests, therapeutics, and vaccine development. Research in the field of antibodies focuses on understanding their structure, function, and production, as well as their potential applications in detecting and treating diseases.