Transpiration is the process by which the water is released into the atmosphere (in the form of water vapours) from the leaves of the plants through stomata.
Stomata creates a suction force that causes the water to rise from the roots and reach the topmost branches of the trees. A major amount of water is utilised in the process of photosynthesis while the excess of water is released from the leaves by the process of transpiration; this in turn makes the roots to absorb more water from the soil.