Question on Lucid Dreaming

I am new on my path and I have so many things about Lucid Dreaming but I have not been able to understand exactly what it is. Now I have been told and read that it is a dream in which you are aware you are dreaming but I have also been told that it is where you know you are dreaming and control the dream. I do not know which it is and am trying to understand. The reason I am wanting to understand this so bad is because I have always even since I was a young child known that I was dreaming in my dreams and every now and then I could control my dreams but now I am unable to control them no matter what I try but I do always know I am dreaming and can remember my dreams no problems.