I have been interested in dreams for many years now. I have kept a Journal of My Dreams since around 1997. There are several different types of dreams. The most common dreams stem from recent events in our lives. Often these events are stuff from the day before or from movies we have recently seen. Other dreams may symbolize different aspects of our lives, or what is happening in our lives on different levels that we are not consciously aware of. We can learn a lot about ourselves by looking at the kind of dreams we have.
Sometimes people will dream about events that have not happened yet. Like the death of someone close to them, or perhaps they will dream about a house they have never seen before, then a few years later when they move they recognize the house they have moved into from the dream.
Some people will try to use dreams to learn more about their past lives. This can be very difficult because it is hard to tell if you are actually dreaming about a past life, or if your mind is just making the stuff up because it thinks it is what you want to see.
One of my favorite categories of dreams are lucid dreams. A lucid dream is a dream where you realize you are dreaming within the dream. Once you are aware that you're in a dream you can do anything you want. You are only limited by your imagination. You can do things like fly around, breath underwater, walk through walls, make things appear or disappear and go anyplace you want. It is very easy to Learn How to Have a Lucid Dream.
If you have trouble remembering your dreams you may want to Learn How to Remember Your Dreams before you try to experiment with lucid dreams. It does no good to have a lucid dream if you can't remember it.