Chemical reaction is a process where substances change into new substances. The starting materials are called reactants, and the new substances are called products. These reactions can take place in many settings, including nature and laboratories. Examples include burning, rusting, and digestion.

Chemical reactions are found in living organisms, the environment, and industrial processes. They can produce gases, heat, light, or solid materials. Scientists study these reactions to understand different substances.

Chemical reactions have been observed and studied for many years. They are part of many natural and human-made processes. These reactions occur in many places on Earth and beyond.