A reagent can be described as a substance that is used to initiate an chemical reaction or verify the existence of an chemical reaction. They are employed to determine if a different chemical substance was introduced into the reaction, typically through changing color. Reagents are often confused as catalysts. They are both substances that serve to boost chemical reactions.

The most important distinction in catalysts and other reagents could be stated as follows:

• Catalysts alter the rate of the reaction by decreasing the energy of activation. They do not consume energy and they don’t directly participate directly in the process.
• Reagents are catalysts for chemical reactions, but they don’t alter the rate of reactions. Reagents can or might not be used in chemical reactions.

Differently from catalysts, reagents can possibly be altered by participating of chemical reaction.