PAMPs, or Pathogen-Associated Molecular Patterns, are molecules found on the surface of pathogens like bacteria, viruses, and fungi. They serve as signals that alert the immune system to the presence of these harmful invaders. Examples of PAMPs include lipopolysaccharides from bacterial cell walls and flagellin from bacterial flagella. When the immune system detects PAMPs, it triggers an immune response, activating various immune cells to fight off the infection. This process is crucial for the body's defense against diseases and is a key concept in immunology, helping researchers develop vaccines and treatments for infections.