Transpiration is the process of plants in which they absorb, distribute and subsequently release water. Evaporation is the movement of water to the air, while guttation specifically refers to secretion of droplets of water from the pores of plants. Both processes combined make up transpiration in plants.
Water potential drives the uptake of water from the root hairs and also in transporting water to the tips of leaves. When evaporation is high in leaves, this creates areas with lower water potential, or areas with less water, so water from the roots and stem is driven to the leaves.
Transpiration allows carrying water and nutrients towards the photosynthesizing parts of the plant, and thus allows plant growth.
Some plants in hot and arid environments open their stomata for gas exchange at night in order to reduce water loss. Some others have reduced leaf surface area, fewer stomata, or hairs on their leaves. On the other hand, in humid environments such as rainforests, plants transpire quickly in order to outgrow their competing neighbors or grow tall enough to avoid being eaten by herbivores.
We can learn how plants adapt to different environments. Moreover, we can study how current environmental changes affect plants and their ecosystem. Moreover, we can also use transpiration studies to identify crops that can grow in a specific climate.
