It is as if our brain takes conscious and unconscious information and reflect them to a new world where new images are formed using this information, we always dream of familiar places but they never are like the real life and in those places happen hypothetical situations to see the result then you will be aware of a possible result and will know how to handle these situations if they happen in real life. It's like a hypothetical universe. Carl Jung described dreams as messages to the dreamer and argued that dreamers should pay attention for their own good. He came to believe that dreams present the dreamer with revelations that can uncover and help to resolve emotional or religious problems and fears. Jung wrote that recurring dreams show up repeatedly to demand attention, suggesting that the dreamer is neglecting an issue related to the dream. He believed that many of the symbols or images from these dreams return with each dream. Jung believed that memories formed throughout the day also play a role in dreaming. These memories leave impressions for the unconscious to deal with when the ego is at rest. The unconscious mind re-enacts these glimpses of the past in the form of a dream. Jung called this a day residue. Jung also argued that dreaming is not a purely individual concern, that all dreams are part of "one great web of psychological factors.

but it doees not make right answers :P

Dream is strange thing. But still science and religion has answer for it. According to science dream comes from 3 types of conditions. One: when we sleeo brain doesnt sleep. But it cant work properly too. Because our all body organ relax when we sleep. So that time brain has no work to do. That is why it keep playing with memories, thinkings, and mix all the things. And we can see it from our inner eyes. Two: if we think about something all day, or tense about something, brain get pressure and this makes a deep impact on brain. So when we sleep brain try to relax by taking out all pressure. That makes dream too. Three: sometime our unconcious mind think a lot of things that we do not know, these things store in a part of brain so when we sleep brain try to relate it with concious mind. That is the time we see dreams. According to religion: dream can be three type. One: devil comes to our mind and make us dream. These dreams are bad dreams. Two: God want to warn someone or try to give indirect message then people see dream. Three: brain become so tired. So when we sleep, it try to take out all the waste thinkings and try to be fresh. So that time we see dreams..