Main contents are about sleeping and dreaming in general, dream interpretation, lucid dreaming.
It generally happens when you realize during the course of a dream that you are dreaming, perhaps because something weird occurs. Most people who remember their dreams have experienced this at some time, often waking up immediately after the realization. However, it is possible to continue in the dream while remaining fully aware that you are dreaming. Usually lucidity brings with it some degree of control over the course of the dream. How much control is possible varies from dream to dream and from dreamer to dreamer.