A monocyte is a type of white blood cell that plays a crucial role in the immune system. These cells are part of the body's defense mechanism, helping to identify and eliminate pathogens like bacteria and viruses. Monocytes are produced in the bone marrow and circulate in the bloodstream before migrating to tissues, where they can differentiate into macrophages or dendritic cells. Monocytes are characterized by their large size and kidney-shaped nucleus. They are essential for phagocytosis, a process where they engulf and digest foreign particles. Additionally, monocytes help in the inflammatory response and contribute to tissue repair, making them vital for overall health and immunity.