Pattern recognition receptors (PRRs) are proteins found in the immune system that help detect pathogens, such as bacteria and viruses. They recognize specific patterns, known as pathogen-associated molecular patterns (PAMPs), which are unique to these harmful organisms. By identifying these patterns, PRRs play a crucial role in initiating the body's immune response. There are several types of PRRs, including Toll-like receptors (TLRs) and NOD-like receptors (NLRs). These receptors are located on the surface of immune cells or within their cytoplasm. When PRRs bind to PAMPs, they trigger signaling pathways that lead to inflammation and the activation of other immune responses, helping the body fight infections.