Two types of 3D:
Active
Passive
Active Requirements: You need a monitor with 120+Hz of frequency (can use lesser frequencys, but you loose fluidity) (check the brand's specs), and Active glasses(>100$). Wht this 3D does is, flash two different images consecutevely, and when the left picture is shown, the left shade is darkened, and vice-versa, confusing your brain into overlapping the pictures, generating 3D.
Pros: no light or color loss. Almost all new Monitors are ready
Cons: High Cost glasses, energy usage
Passive Requirements
Two essential types:
Circular polarization: Two different images are generated at the same time, but are displayed by two different displays (could be in the same monitor, or two different projectors), and the image is separated for each eye by the light polarization filter lens, different for each eye.
Pros: Cheap Glasses
Cons: light loss, costier monitors or double projector + light filters and stuff
Color polarization:
The red/cyan/green one. The images are filtered, each of the eye maintaining one given color channel. The glasses then filter by color these images,
generating 3D.
Pros:Cheap technology, available for any colored screen
Con: Color loss mainly, but huge