In a chemical reaction, reactants are consumed and products are formed. A product is a substance that results from the reaction. It appears on the right side of the chemical equation. In the combustion of methane, CH4 + 2O2 -> CO2 + 2H2O, the products are carbon dioxide and water. The arrow means yields or produces. The equation is balanced so that the number of atoms of each element is the same on both sides.

The amount of product formed depends on the limiting reactant. If one reactant runs out before the others, the reaction stops, and the amount of product is determined by that reactant. The theoretical yield is the maximum amount of product that can be formed. The actual yield is what is obtained in practice. The percent yield is the actual yield divided by the theoretical yield, multiplied by 100. Yields are rarely 100 percent because of side reactions, incomplete reactions, and losses during purification.

Products can be solids, liquids, gases, or aqueous solutions. Their states are indicated in the equation with symbols. Products can be stable or reactive. They can be the desired product or an unwanted byproduct. In industry, maximizing the yield of the desired product and minimizing byproducts is a major goal.

The word product is also used in mathematics, where it means the result of multiplication. In chemistry, it means the result of a reaction. Context determines the meaning.