Lipopolysaccharide (LPS) is a large molecule found in the outer membrane of Gram-negative bacteria. It consists of a lipid portion, known as lipid A, and a polysaccharide component. LPS plays a crucial role in the structural integrity of the bacterial cell wall and helps protect the bacteria from harmful substances. When released into the body, LPS can trigger strong immune responses, which may lead to inflammation. This can be beneficial in fighting infections but can also contribute to severe conditions like sepsis if the response is excessive. Understanding LPS is important for developing treatments for bacterial infections.