A pesticide is a chemical substance used to kill or control pests, which can include insects, weeds, fungi, and other organisms that harm crops or spread diseases. Pesticides are commonly used in agriculture to protect plants and improve crop yields, ensuring a stable food supply. They can be classified into different categories, such as insecticides for insects, herbicides for weeds, and fungicides for fungi. While pesticides can be effective in managing pests, they can also pose risks to human health and the environment if not used properly. It is important for farmers and users to follow safety guidelines and regulations to minimize potential negative impacts on biodiversity and ecosystems.