Herbicide is a substance toxic to plants, typically used to control weeds. It is a type of pesticide, which is a chemical or biological agent used to kill or control pests. Herbicides are widely used in agriculture and gardening to control weeds and other unwanted plants. They can be applied directly to the target plant or sprayed over a large area. Herbicides can be selective, meaning they only affect certain types of plants, or non-selective, meaning they affect all plants.