Antibodies, also known as immunoglobulins (Ig), are small proteins that play a vital role in the human immune system. They are produced by plasma cells upon exposure to foreign substances called antigens. These antigens could be viruses, bacteria, toxins, or any other foreign entity that enters the body. Antibodies recognize and bind to these antigens, leading to their elimination from the body. In fact, antibodies constitute 20% of plasma protein in the human body. The discovery of antibodies is attributed to Emil von Behring, who discovered antitoxins for diphtheria, tetanus, and anthrax.