What is the function of white blood cells?

White blood cells (WBCs), also known as leukocytes, play a critical role in the immune system by defending the body against infections, bacteria, viruses, and other harmful invaders. They circulate in the bloodstream and are able to detect foreign substances, which they then neutralize or remove. There are several types of white blood cells, including neutrophils, lymphocytes, and macrophages, each performing specialized functions in immune responses. WBCs also contribute to inflammation and help the body heal from injuries.