Bacterial endotoxins are toxic substances found in the outer membrane of certain types of bacteria, particularly Gram-negative bacteria. They are composed of lipopolysaccharides (LPS) and can trigger strong immune responses in humans and animals. When these bacteria die or are destroyed, endotoxins are released into the surrounding environment, potentially leading to inflammation and fever. Endotoxins are significant in medical settings, especially in the context of sepsis, a severe response to infection. They can also affect the safety of pharmaceutical products, making it essential to test for endotoxins in injectable medications and medical devices to ensure patient safety.