Complement activation is a crucial part of the immune system that helps the body fight infections. It involves a series of proteins that work together to identify and eliminate pathogens, such as bacteria and viruses. When these proteins are activated, they can directly destroy pathogens or mark them for destruction by other immune cells. There are three main pathways for complement activation: the classical pathway, the lectin pathway, and the alternative pathway. Each pathway is triggered by different signals, but they all lead to a common outcome: the formation of a complex that enhances inflammation, attracts immune cells, and promotes the clearance of harmful invaders.