The rain: it is water that falls from the atmosphere to the ground in the form of drops, the rain is formed with the water of seas, rivers and lakes, the heat evaporates the water and turns it into steam, rises to the atmosphere, when it rises, It cools and countess, that is, it turns into small drops of water, that droplets are swollen around tiny particles of dust.
When the water vapor condenses, clouds form, when the drops are too big and heavy so that the air currents can sustain them, they fall to the earth in the form of rain, sometimes the water vapor crystallizes in flakes of snow, usually the temperature lower than 0ºC, and then falls to the ground.
The process by which rain is formed is an infinite cycle, water that falls as rain evaporates and rises in the air and falls again, rain is necessary for all forms of life, rain provides clean water You need the animals and the humidity that the plants require.
Rain is a natural phenomenon that is part of the water cycle and therefore its presence for life is vital. Without rain or precipitation the water cycle would be interrupted and the existence would not be the same since the soils would not be watered, the vegetation would not grow and the food chain could not begin.
Rain is just a form of precipitation, other forms of precipitation are snow, sleet and hail.
Image source: http://arcanastu.blogspot.com/2014/01/me-gusta-la-lluvia.html