White blood cells, or leukocytes, play a crucial role in the immune system. They are responsible for identifying and attacking pathogens like bacteria, viruses, and other foreign invaders that threaten the body's health. White blood cells are produced in the bone marrow and circulate through the bloodstream and lymphatic system. There are several types of white blood cells, each with specific functions, including phagocytes that engulf pathogens and lymphocytes that produce antibodies. Their ability to adapt and respond to infections is vital for maintaining overall health and preventing diseases.