Some advanced TVs and other high-tech kit can display 3D images without the need for the traditional 3D glasses – and this guide explains a bit about how it works.
Glasses-free 3D works in a similar way to traditional 3D. With traditional 3D, there are two video streams playing: one for the right eye and one for the left. 3D glasses split the correct video stream to the correct eye. Even the old-fashioned red and blue glasses do a similar job.
The same applies for glasses-free 3D – except that the TV does the hard work. The display has an extra layer called a 'parallax barrier' which directs the light to the correct eye. The Nintendo 3DS games console introduced this technology in 2011, and is one of the most popular uses of glasses-free 3D.
One drawback is that this type of 3D needs you to be positioned in a 'sweet spot' to get the full effect. This isn't too much of a problem on a handheld like the 3DS, because it's easy to move the device iteself around – but TVs are in fixed place, so it's you that has to move.
That said, the technology is always improving – and there are already some newer TVs that don't have this problem.