Dreaming has been called everything from a "subconscious reading between the lines" to communication from God. While dreaming, we apparently process chaotic information in our minds in the form of a visual "screenplay." When we remember them, it's because we've viewed them with a conscious mind and recorded them in our memory.
There are a lot of different types of dreams: eposidic, flying, repetitive, precognitive, shared, universal, just to name a few, and lucid. Lucid dreams are when you realize you are dreaming and you can actually alter the events in the dream. It appears that some people have lucid dreams easily, while others have to learn how to do them. It also appears that anyone can learn how to have them.
This has to do with the three major states of consciousness that all of us are familiar with: waking, dreaming, and sleeping, or gross, subtle, and causal states. Dreams occur while surfing the subtle state - between the gross world of matter and the emptiness of causal deep sleep.
I've started a self-guided program to induce lucid dreaming into my practices, and have begun keeping a journal of my dreams. There are a couple of reasons for this: I want to see if there are any recurring messages my subconscious might be sending me, and, by becoming aware of my dreams, I might be able to identify those repetitive dreams as they are occurring, and control them. Why control them?
Lucid dreaming can be used to ask for guidance. It can help people face and overcome fears and inhibitions that might be preventing them from getting the most out of life. It can help people overcome nightmares. It can be used to gain knowledge about ourselves and grow spiritually.
Adventure and fantasy/overcoming nightmares/rehearsal/creativity and problem solving/healing/transcendence......