White blood cells, or leukocytes, are a crucial part of the immune system. They help the body fight infections and diseases by identifying and attacking harmful pathogens like bacteria and viruses. There are several types of white blood cells, each with specific functions, including neutrophils, lymphocytes, and monocytes. These cells are produced in the bone marrow and can be found in the bloodstream and lymphatic system. When the body detects an infection, white blood cells quickly move to the affected area to combat the invaders, helping to keep the body healthy and functioning properly.