8/12/2009 or 12/8/2009?

I had a discussion with a colleague today about how numerical dates are written in America (US and Canada) versus Europe (or even the rest of the world). In America, the numerical dates are written as Month / Day / Year, so today's date (August 12th, 2009) is written as 8/12/2009. In Europe, the numerical dates are written as Day / Month / Year, so today's date is written as 12/8/2009. As you can see, there could be a lot of confusion between Americans and Europeans when talking about dates. Does 8/12/2009 mean August 12th, 2009 or December 8th, 2009? Bad for communication...

I tried looking up the origins of these two representations but couldn't find any reliable sources. On the unreliable sources front, some people think that these numerical representations were simply shortened forms of dates written in English and the difference is simply the result of differences between American English and British English. In American English, dates are written as Monthname Day, Year, so today's date is written as August 12th, 2009 and the numerical (shorten) representation is 8/12/2009. In British English, dates are written as Day Monthname Year, so today's date is written as 12th August 2009 and the numerical representation is 12/8/2009. This explanation makes totaly sense but I couldn't find a reliable reference...

In my opinion, it's much better to use "2009-8-12" instead of the above-mentioned representations. Why? It helps your brain narrow down on the dates more logically as you read through it. Let's look at the European format (12/8/2009). As you read through it, your brain will learn that it's the 12th day of a certain month in a certain year (not very specific at all); then your brain will figure out it's the 12th day of August in a certain year (a little better but there are at least 2000 possible dyas). Now, let's look at "2009-8-12". As you read through it, your brain will learn that it must be some time in Year 2009 (only 365/366 days to consider), then your brain will find out it's some time in August of 2009 (31 days), and lastly, your brain will identify it as the 12th day of August in 2009. It's very logical and helps your brain narrow down on the specific day much quicker. Anyway, if you are interested, "2009-8-12" is referred to as the ISO 8601 standard. Come to think of it, Chinese actually uses this standard, 2009年8月12日.

You can check out Wikipedia - Calendar date for more information.