Melting is defined as the process in which a solid changes to a liquid state without any change in temperature. This process of melting is also known as fusion. The amount of heat required to convert 1 kg of a solid into its liquid state at atmospheric pressure, without a change in temperature (i.e., at its melting point), is called the latent heat of fusion.
Melting or fusion is a physical process that results in the phase transition of a substance from liquid to solid. this occurs when the internal energy of the solid,increases typically by the application of heat and pressure,which increases the substance's temperature to the melting point.