Lucid dreaming from wiki:
A lucid dream is any dream in which one is aware that one is dreaming. In relation to this phenomenon, Greek philosopher Aristotle observed: “often when one is asleep, there is something in consciousness which declares that what then presents itself is but a dream“.
Often when I’m dreaming, I’m looking for a pre-lucid state so I can determine whether I’m dreaming. Why? Because when you’re lucid, you can control what you do and see in your dream. You can make the bad guy powerless. You can fly. You can ask questions of your subconscious (which is connected to other peoples and places) and get answers to many different questions.
The caveat. If the stimulus of being lucid is too great, you wake up.
The key is mastering how to stay in the dream.