What do we mean by latent heat?

When heating a substance, the particles gain energy. As you heat a solid, it eventually changes to a liquid and if you continue to add more heat, it will eventually turn into a gas. When a solid turns into a liquid, we call it melting. When a liquid turns into a gas, we call it boiling. melting and boiling are words used to describe a substance that is CHANGING state. The amount of energy needed to completely change a substance from one state to another is called LATENT HEAT. Specifically, there are two type of latent heat; 'latent heat of fusion', and 'latent heat of vapourisation'. Can you think which one relates to which change of state and why? (If they require further prompting, or simply need to be told then this explanation follows). Latent heat of fusion refers to the energy needed to change a solid to a liquid; hence the word fusion. Whereas latent heat of vapouridation refers to the energu needed to completely change a liquid to a gas, hence the word vapourisation.