Do only Canadians call these Robertson screws? That's what I know them as.

Yes, these screws were invented by a Canadian - Mr. Robertson of course - but they are now used all over the world. The screwdrivers are great to use one handed and they never slip out of the screw.

along with these, you can find all kinds of great, unique screws. often they're called security screws. For example if you look at a abthroom stall the often have funny looking screws that a normal phillips head would slip when trying to loosen. All so that people don't mess with the structure.

You can often find a set of bits cheap that are all different types of security screws.

My favorites are the square one pictured then one that just has two small holes

two holes? I've never seen such a screw.

I like the robertson screws, but have never thought of them as design details.

Peter Lymburner Robertson (1879-1951)

After badly cutting his hand while using a slot-headed screwdriver, Peter Lymburner Robertson invented the square-headed screwdriver and screw in 1908. He received the Canadian patent for his invention in 1909. A person could drive a screw more quickly with this new design and the screw was self-centering so only one hand was needed. On top of that, the driver fit more tightly in the screw's head, thereby reducing the chance of the screwdriver slipping out.

The Robertson screw was a big hit! Industry loved it because it sped up production and resulted in less product damage. No one has been able to improve on this design in all the years that have followed!

i've always called the two hole screws 'prison screws.'

no joke.

love the robertson screws as well but never thought of them in terms of escalating design but rather serve a functional purpose...the tool doesn't slip out the tophead.

I love that non-Canadians find this to be such a novelty. They are everywhere here...thanks for helping us to see the beauty in small details!

They are widely available here too. Another source is Lee Valley (or leevalley.com) which funny enough is a Canadian company if I am not mistaken but they have shipping sites here in the US. They have a good selection of screws too in different finishes as well as a very large and well priced selection of hardware. I'm a cabinet/furnature designer and I build all of my designs. I use them a lot and have been very happy with their service and selection.

The "square head" are called "Robertson". http://en.wikipedia.org/wiki/Robertson_screwdriver
They were invented by a Canadian, and it's very common here in Canada. They were invented after the flathead, to combat the problem of having to use both hands to do the job. The square is tampered slightly which would be catched by the screwdriver, thus free up the other hand.

They are easier to screw in, but extremely hard to screw out, and easily damaged. Hence the invention of Philips, which is easy both going in and out.

Robertsons remain popular for public places, like subways and elevators that you mentioned, to prevent vandalism. (Swiss Army knife usually comes with philips and flats.)

There are many different kinds of screw heads these days. Rather than aesthetic reasons, one should also consider practical reasons. If you would need to take the furniture apart for moving, you might not want to use Hex or Robertson.

In an episode of "King of Queens", Arthur (played by Jerry Stiller) was trying to push his design of "A-head Screwdriver" that would fit into the "A-Hole". lol

Evil Tofu's comment:
" If you would need to take the furniture apart for moving, you might not want to use Hex or Robertson."
made me laugh-
I once helped an artist in the studio down the hall, to make a shipping crate, so that he could enter a piece in an exhibition/juried show in Washington DC.
Since I generally prefer the square drive screws in my work as well ,because they don't "cam-out" (I also design and build Custom Furniture), I went ahead and built Michaels crate out of wood, and he got it off to FedEX in time to make the deadline.
A while later- I asked "How he made out", in the DC show.
"Not good"- he responded.
"Why", I asked?
"Well, they couldn't open the crate you made.
They didn't have the same screw driver that you used."

So much for "helping" a friend......

I figured there would be a lot of Canadians commenting here!

Self-assembly furniture here in the UK uses hexagonal allen key screws a lot, and I have to say, so far about 30% of them end up with the allen key gouging a big round hole that renders the screw useless - a problem I've never had with Philips screws, no matter the size.

Maybe it's due to cost-cutting and shoddy screw material, but my heart sinks when I open a new piece and see an allen key in there, and I almost always end up making a trip to the hardware store for some proper screws!

Haha...look at all of us Canadians. I really had no idea that these weren't common everyday types of screws in the rest of the world.