What are antibodies and what is their significance in the human body?

Antibodies are small proteins that circulate in the bloodstream. They are part of the body’s defense (immune) system and are sometimes called immunoglobulins. They are made as white blood cells (B-lymphocytes). Antibodies attach to proteins and other chemicals in the body that they recognize are usually not found in the body (“foreign”). Foreign proteins and chemicals to which antibodies are attached are called antigens.
Antibodies help protect us from infection. Bacteria, viruses, and other microbes have proteins on their surface called antigens. The immune system recognizes antigens as foreign. So, when we have certain infections, the B cells make many antibodies that attach to the infecting microbes.