Chemical warfare refers to the use of toxic chemicals such as gas, liquid or solid substances to inflict harm on people, animals, or the environment. Synonyms for chemical warfare include chemical weapons, biochemical warfare, toxic warfare, poison warfare, and gas warfare. Chemical weapons are harmful substances that can cause severe health problems to those who are exposed to them. Biowarfare involves the use of microorganisms like bacteria and viruses to cause harm. Toxic warfare refers to the release of hazardous or poisonous substances into the environment. Poison warfare is the use of poisonous substances to harm people. Gas warfare involves the deployment of gases like mustard, chlorine, or nerve gases to cause harm.