Latent heat

It is the heat supplied to the matter of 1kg weight to change its state at constant temperature. If the solid can be changed into liquid at constant temperature by appyling the heat. This heat is called 'latent heat of melting or fusion'.
A liquid can be changed into vapour at constant temperature by applying the heat. This heat is called 'latent heat of vapourisation.
Some liquids have low latent heat of vapourisation called volatile liquids. Ether and petrol are the examples of volatile liquids because these liquids get vapourised quickly.