The complement system is a part of the immune system that helps the body fight infections. It consists of a series of proteins that work together to identify and destroy pathogens, such as bacteria and viruses. When activated, these proteins can directly kill pathogens, mark them for destruction by other immune cells, or promote inflammation to recruit more immune responses. The complement system can be activated through three main pathways: the classical pathway, the lectin pathway, and the alternative pathway. Each pathway has different triggers but ultimately leads to the same outcome—enhancing the ability of the immune system to eliminate threats and maintain health.