Lucid dreaming is when a sleeper realizes that they are in a dream. It is possible for a sleeper to attain lucidity within a dream by having their attention drawn to the strangeness of the dream (the Mr. Charles tactic is an example of this) or already knowing that they are dream sharing. One method for checking the artificiality of a dream is through the use of a totem.
While lucid dreaming in a normal dream, it is possible to control the dream. A dreamer can control a dream while Dream-Sharing whether they are lucid or not, but being lucid allows them to control a dream consciously.
It is also possible for one to lose their lucidity by becoming "lost" within a dream. This can happen through several methods including by dying within a dream and waking in Limbo with no bearing for reality, or by inserting memories into one's dream, and mistaking them for reality.