The immune system is broadly divided into two main components: the innate immune system and the adaptive immune system. The innate immune system provides the first line of defense and includes physical barriers like the skin, as well as immune cells such as macrophages and neutrophils. The adaptive immune system, on the other hand, is more specialized and involves lymphocytes such as T cells and B cells, which have the ability to remember specific pathogens for a faster response upon subsequent exposures.
