Neutrophils are a type of white blood cell and a key component of the immune system. They are the most abundant type of granulocyte and play a crucial role in the body's defense against infections, particularly bacterial and fungal infections. Neutrophils respond quickly to sites of infection or inflammation, where they engulf and destroy pathogens through a process called phagocytosis. Additionally, they release enzymes and antimicrobial substances that help to eliminate invading microbes.