What are fusion and melting point? On what does the value of melting point depend?

(N/A) Fusion is the process of phase transition in which a substance changes from a solid state to a liquid state by the absorption of heat at a constant temperature.
The melting point is the specific temperature at which a solid substance changes into its liquid state at a given pressure.
The value of the melting point depends on the following factors:
$1$. Nature of the substance: Different materials have different intermolecular forces,leading to different melting points.
$2$. External pressure: For most substances,an increase in pressure increases the melting point. However,for substances that contract upon melting (like ice),an increase in pressure decreases the melting point.