Toll-like receptors (TLRs) are proteins found on the surface of certain immune cells. They play a crucial role in the body's defense system by recognizing harmful substances like bacteria and viruses. When TLRs detect these invaders, they trigger an immune response, helping the body to fight off infections. There are several types of TLRs, each designed to identify different pathogens. For example, some TLRs recognize bacterial components, while others detect viral elements. By activating immune responses, TLRs help to initiate inflammation and recruit other immune cells to the site of infection, enhancing the body's ability to protect itself.