Burning a match is a chemical reaction because the reactant, primarily wood, is chemically altered into a different substance, ash. A chemical reaction or change involves one or more reactants having bonds broken or altered to form new substances. In the case of burning a match, wood and oxygen are transformed into ash and smoke, two distinctly new products.
Changes can either be classified as physical or chemical. In a physical reaction, no bonds are broken, and the change can be reversed by mechanical means. For example, water turning into ice is a physical change. The molecules may be in a different state, but they are still all H2O molecules.