There are two types of changes that can occur- chemical and physical. Chemical changes are going to produce a new product. They change the chemical composition of a substance. Examples of chemical changes are burning or decomposition. Physical changes do not produce a new substance. They only affect the appearance of physical attributes of a substance. Examples of physical changes are ripping, smashing, and tearing.
When a liquid changes to a solid, the liquid has not changed into a new liquid. Its molecules have simply lost kinetic energy and come closer together. We cal this freezing, which is an example of a phase change. Other phase changes are melting, evaporating, condensating, and sublimation or deposition. Because no new substances are made, all phase changes are physical changes.