Stoichiometry is a branch of chemistry that deals with the quantitative relationships between reactants and products in chemical reactions. It involves calculating the amount of reactants needed to produce a certain amount of product, as well as determining the amount of product that will be formed from a given amount of reactants. Stoichiometry is based on the principle of the conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction, only rearranged. This field is essential in understanding and predicting the outcomes of chemical reactions, as well as in making precise measurements and calculations in laboratory settings.