The human immune response is the body's defense mechanism against harmful pathogens like bacteria, viruses, and parasites. It involves a complex network of cells, tissues, and organs that work together to identify and eliminate these threats. Key players in this system include white blood cells, antibodies, and lymph nodes, which help recognize and attack invaders. When a pathogen enters the body, the immune system activates, triggering an inflammatory response. This process helps isolate the infection and recruit more immune cells to the site. Once the threat is neutralized, the immune system retains a memory of the pathogen, allowing for a quicker response if the same invader is encountered again in the future.