Agglutination is a biological process in which particles, such as cells or bacteria, clump together due to the action of specific antibodies. This phenomenon is commonly observed in immunology, where antibodies bind to antigens on the surface of cells or pathogens, causing them to stick together and form visible clumps. Agglutination is often used in laboratory tests to detect the presence of specific antigens or antibodies, such as in blood typing or diagnosing infections. The clumping effect is a result of the cross-linking of antigens by antibodies, which can be observed visually or measured to determine the presence and concentration of the target substance.