Pesticides are substances used to kill pests like insects, weeds, rodents, and fungi that damage crops or transmit diseases. They work by inhibiting the metabolic processes of pests. Common types include insecticides, herbicides, rodenticides, and fungicides. Integrated Pest Management is an approach that uses targeted pest control methods like biological and mechanical controls instead of relying solely on chemical pesticides. Choosing the right pesticide depends on the type of pest and habitat. Some natural pesticides come from plants like tobacco, pyrethrum, and derris elliptica.