A pesticide is any substance sold to kill, retard, repel or attract a pest species. Pesticides can be classified according to their target, according to their function, or according to their chemistry. Most of today's pesticides are organic chemicals. Commonly used inorganic pesticides include copper fungicides, lime-sulfur used to control fungi and mites, boric acid used for cockroach control, and ammonium sulfamate herbicides.
Most pesticides used today are synthetic organic chemicals.
They can be grouped into chemical families based on their structure and mode of action in the pest. Important chemical families of fungicides and insecticides are presented here. This group includes both contact and systemic insecticides. They are not as persistent as chlorinated hydrocarbon products but tend to be more toxic to applicators and wildlife. The organophosphate insecticides are nerve poisons and have been involved in most serious human pesticide poisonings.