The camera is what dictates what is shown on the screen, whether or not it simulates the effect of a video camera. It can depict an invisible viewport of the world around the player character, or it could even be showing things as if from the perspective of a character.
Questions under the purview of this tag generally deal with camera positioning, movement, and special effects.
When designing a 3D game, you might also want to take lighting into account when appropriate.
