It has a transmitter to broadcast to the glasses, it usually has a 120Hz or faster display panel, the TV processor is also faster as it can toggle between 2D and 3D.
If you want to watch 3D media, you'll need a 3D compatible TV plus a 3D compatible player such as 3D blueray player. Even the original media is not in 3D, you can use the TV's 3D animated effect to watch 3D-like result.
i hate 3d... know how it works, tried it since the 80s, and tried it in 2012, not anything earth shattering, stupid glasses, darken image, passive? lower resolution. Usually more depth than pops, and that freaking thing makes me dizzy. I'm out.