- They are reversible. This means that the original substance can be restored from the changed substance.

- They do not change the chemical composition of the substance. This means that the atoms in the substance remain the same before and after the change.

- They can be observed without changing the identity of the substance. For example, you can observe a change in the size, shape, or color of a substance without changing what it is.

Common examples of physical changes include melting, freezing, boiling, evaporating, condensing, and sublimation.