Chemical catalysts are substances that speed up chemical reactions without being consumed in the process. They work by lowering the activation energy required for a reaction to occur, allowing reactants to transform into products more efficiently. Catalysts can be found in various forms, including metals, enzymes, and acids, and are essential in many industrial processes. One common example of a catalyst is platinum, which is used in catalytic converters to reduce harmful emissions from vehicles. Another example is enzymes, which are biological catalysts that facilitate reactions in living organisms, playing a crucial role in processes like digestion and metabolism.