B-cell receptors (BCRs) are specialized proteins found on the surface of B-cells, a type of white blood cell crucial for the immune system. These receptors recognize and bind to specific antigens, which are foreign substances like bacteria or viruses. When a BCR binds to an antigen, it triggers the B-cell to activate and proliferate, leading to the production of antibodies. Antibodies are proteins that help neutralize or eliminate pathogens. Each BCR is unique, allowing the immune system to target a wide variety of antigens. This diversity is essential for effectively defending the body against infections and diseases.