The innate immune system is the body's first line of defense against pathogens, such as bacteria and viruses. It consists of physical barriers, like the skin and mucous membranes, as well as immune cells that respond quickly to infections. These cells include macrophages and neutrophils, which can recognize and destroy invaders without needing prior exposure. Unlike the adaptive immune system, the innate immune system does not have memory, meaning it responds the same way to repeated infections. It also involves various proteins, such as complement proteins, that help enhance the immune response. Overall, the innate immune system plays a crucial role in protecting the body from illness.