Chemical and biological weapons are types of weapons designed to harm or kill people through toxic chemicals or infectious agents. Chemical weapons can include substances like nerve agents or mustard gas, which can cause severe injury or death upon exposure. These weapons are often banned under international treaties due to their devastating effects. Biological weapons, on the other hand, use pathogens such as bacteria or viruses to spread disease. Examples include anthrax or plague. Both types of weapons are considered weapons of mass destruction and are prohibited under agreements like the Chemical Weapons Convention and the Biological Weapons Convention.