3D

Okay, so I assume a large majority of you have two eyes. Sorry if you don't.
So two eyes = two different views on the world, albeit slightly different.
When those views are pieces together in your mind, it's called Stereovision.
Basically, the images from your mind arrive in your brain at the same time, and then your brain, clever thing that it is, sorts out the similarities and differences and puts them together.

Why you ask?
So we can create our own mental map of how near or far an object may be. And it was probably done becaue of predators, no point in looking at something and thinking it's miles away when it's really in front of you.
Which brings me to the next point.

Depth Perception
The brain has all these tricks to make us notice when something is far away or close up, they're called Depth Cues. And these include stuff like:

Focus- If you can see details on say, a gravel path. The closer it is, you can see more stones, but the further and it just seems like a blur, hence the Focus.

Occlusion- if something obstructs another object, you assume the one doing the obstructing is the one closest to you.

Linear Perspective- things like vanishing points. Like how if you stand at one end of a street the other end seems to meet in a point, the further along it is, the further away the object is.

and Vertical Position- if something is higer up on your view, you assume it's further away.

I hope that's kinda explained, harder than I thought to do so.

SO! 3D GLASSES!
I love 3D, gimmick or not, part of it, is getting the glasses. You know, way back when, when it was the typical red and blue glasses, also known as 'anaglyph' but know you get the kinda stripey, grey ones.
Anaglyph glasses work in the way that the red side only lets red objects pass through and the cyan (not blue, people), only let everything..not red through..
So your brains gets two different images.. and sorts out the differences and similarities out and puts them together and voila! We see in 3D.
The first 3D films was apparently created in 1915, but it wasn't til the 1950's where we started to pick up on it a lot more.

Polarised Glasses are what a majority of cinemas use now (unless they're rich and use the electronic shutter glasses, which shutter between images funnily enough).
Polarised glasses, have a filter in the lens, which is at a different angle to the other lens, normally at about 90 degrees apart, therefore seeing different images and then brains sorts them, and you see in 3D.
(Then you get out of the cinema and kids think they're so cool to pop out the lens and put on these thick rimmed glasses. It's not. If you want glasses, have bad eyes like the rest of us.)

My View
The first 3D film, I went to see was Alice in Wonderland, the Tim Burton version, it was okay but the fast bits blurred a bit, not too impressed.
Since then, I've also seen: Clash of the Titans (same problem), How to Train your Dragon (too worried about wanting a Toothless to care) and Avatar, and Harry Potter 7 part 2, and Puss in Boots and probably a bit more than that.
I quite enjoyed a lot of them, I wouldn't go to the cinema just because something was 3D, but I wouldn't mind watching it in 3D, I'm not out rushing to buy a 3D screen either.
What I do want though is a 3DS, but that's for the pure fact a game from one of my favourite franchises are coming out on it.
And I'll leave you with that, see you next time~


References
 HAL MORGAN and DAN SYMMES (1982) Amazing 3D, Canada: Little Brown and Co pp. 165–169.

Julius B. Kaiser (1955) Make Your own Stereo Pictures, New York:The Macmillan Company page 271