Exotoxins are toxic substances produced and secreted by certain bacteria, such as Clostridium botulinum and Staphylococcus aureus. These proteins can cause damage to host cells and tissues, leading to various diseases. Exotoxins are often released into the surrounding environment, where they can affect nearby organisms. Unlike endotoxins, which are part of the bacterial cell wall and released when bacteria die, exotoxins are actively secreted during bacterial growth. They can trigger strong immune responses and may be used in vaccines, such as the tetanus vaccine, to help the body build immunity against specific toxins.