Lipopolysaccharides (LPS) are large molecules found in the outer membrane of Gram-negative bacteria. They consist 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 cause severe reactions, such as septic shock, if the immune response is excessive. Understanding LPS is important in fields like microbiology and immunology.