Explain transpiration?

Transpiration is the process by which excess water evaporates from the surface of leaves of a plant through stomatal pores.

Transpiration causes a vacuum or a suction pull inside the vessels, which is similar to that created on drinking liquid using a straw. Such a suction pull enables xylem to work against gravity and transport water from the roots to the leaves of a plant. The process of transpiration also helps the plant to cool.