B-cells are a type of white blood cell that play a crucial role in the immune system. They are responsible for producing antibodies, which are proteins that help identify and neutralize pathogens like bacteria and viruses. B-cells develop from stem cells in the bone marrow and can differentiate into various forms, including memory B-cells, which provide long-term immunity. When a B-cell encounters a specific antigen, it activates and begins to multiply. This process leads to the production of antibodies that specifically target that antigen. The effectiveness of B-cells is vital for the body's ability to fight infections and is a key component of the adaptive immune response, alongside T-cells.