Transpiration is the name given to the process of evaporation of water molecules from the stomata in leaves. It is an important process as-
i) this evaporation during transpiration creates a suction pull which facilitates the upward movement of water and dissolved minerals in the xylem from the roots to leaves.
ii) transpiration helps in temperature regulation of the plant body.
iii) this way the plants are also able to get rid of excess water in their bodies.