Cytotoxic T lymphocytes, also known as CD8+ T cells, are a type of white blood cell that plays a crucial role in the immune system. They are responsible for identifying and destroying infected or cancerous cells. These cells recognize specific antigens presented on the surface of target cells, allowing them to target and eliminate threats effectively. Once activated, cytotoxic T lymphocytes release toxic substances that induce apoptosis, or programmed cell death, in the infected or abnormal cells. This process helps to control infections and prevent the spread of diseases, making cytotoxic T lymphocytes essential for maintaining overall health and immune defense.