White blood cells, or leukocytes, are a crucial part of the immune system. They help protect the body from infections and diseases by identifying and attacking harmful invaders like bacteria and viruses. There are several types of white blood cells, each with a specific role, such as neutrophils, which quickly respond to infections, and lymphocytes, which help remember past invaders to fight them more effectively in the future. 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 move to the affected area to combat the threat. A healthy balance of white blood cells is essential for maintaining good health and preventing illness.