A person having such a dream knows that they are having the dream (that is, in effect, the definition). And so does everyone else. We've all seen this person -- the one who may be staring right at the speaker (be it in a classroom, church, seminar, conversation) and yet also be appearing to stare right through the speaker. this far off look is definitely indicative of that person's mind being "somewhere else".
After looking through tons of resources I have collected together a few sites for you to put your hands on . . .
This is a good sight to learn some more general information on lucid dreaming. It is easy to follow while very informative.
This is a more technical site but good for those with a scientific and statistical mindset. This will give you some concrete evidence and information on the subject.
This is some more extensive research done by a very good doctor, Dr. LaBerge. This site is defintely worth trying out for yourself.
Yes, it is true. There is a whole book provided on here about the subject. It is very organized and very useful. It is even broken up into chapters. Check it out!!
For the real serious "luciders" this site is a must. It's mission is "dedicated to the advancement of research and the nature and potentials of consciousness and to the application of the results to the enhancement of human health and well-being.