Why do we dream science explanation

When we fall asleep we all have some dreams.well so whats the definition about dreams then? According to Wikipedia"Dream are the things which we see involutarily see when we are fall asleep that may represent images,ideas and our thought".so the question arise do we all have dream so the answer is yes .We all people have some dreams.If we all have dream then what a blind people see if they are blind from their child.So if they are blind then there is complete darkness in his dreams but due to the sense of hear , touch and other sensations they dreams .We cannot remember all the dreams most of the dreams which we see at night we forget all that dreams and only a few portion are remembered .Why do we have dream the science cant explain why we dream and what the science behind dream.Though some psychyatrist and scientist can explain about it in their own.
According to sigmund freud a well known psychologist has explained it in his way according to him in our day to day life we have many things that come to our mind some of the things we can express while some cant due to our society taboos and restrictions and when that things come up in our mind and stimulate us now they become a burning desire and to full fill it dream comes if some one has a burning desire to buy a car then he sees it in his dreams because during sleep the brain is relaxed and no any intelligence and supression come before it.We are fully relaxed and now our mind will shows us the dream which we have imagine.Just like in teen agers the dream which the youths see is wet dreams why this occur then because teen ager is a transition period of child to youth and a great harmonal change takes place during this period due which there is a strong attraction force between opposite sex and they cant full fill their desire to have physical relation as due to restriction and taboos of the society,so they have wet dream.

The people also has the mentality that the dreams serve as intermediate between the future and the presents.People predict the future of the people by the dreams they see at night during sleep.In dream where we can know that we are having dream then such dream is called "Lucidity dream".Some of the mythology also confined it as a event that occur before our birth in previous life but this is not possible in terms of science as science is leaping only because of proof and reasons but there is not such real proof so it is not given much preference.Dream also changes from person to person on the basic of nature and habits of people their attitude and ages due to which the dream varies from person to person.

However all those facts also if we take a deep and serious look at the dream then we will find a surprising and amazing but reality which has no appropriate reasons to describe and its occurence is also mysterious in todays time .Which we always see but do not notice but at last dreams are dreams having some connection with our lives but that do not carry any negative sign because it depends on our ways of visualizing and thinking