How CAPTCHA Works - Fun Fact - I'm Not A Robot!

It's true! I once fell and scrapped my knee and actual human blood came out! But that is not really what this article is about. Today I would like to share a fun fact I learned not too long ago about CAPTCHA.

There is no doubt that all of you have encountered CAPTCHA in one form or another over the course of your life. Originally CAPTCHA would require users to type out a few distorted letters/numbers shown in a picture in order to filter out any robots (specifically computer software) trying to perform whatever task the website was based on. Nowadays, CAPTCHA has upped the bar requiring users to perform tasks such as selecting only images in a set that contain specific elements such as signs, buildings etc. Something that, at this point in time (until the AI revolution makes some major strides), computers are not all that good at. However, recently CAPTCHA has taken on a different form. Likely due to consumer complaints based on the increasing dificulty, Google introduced what they call "No CAPTCHA reCAPTCHA". Most of you probably know of "No CAPTCHA reCAPTCHA" as the "I'm not a robot" button that has replaced the original CAPTCHA system on many websites. For the longest time I had no clue how this button worked, since clicking a box is something that computer software bots are actually very good at...

Want to know you it works?
This is the part that will probably blow your minds. While visiting a page with a "I'm not a robot" button there is a mouse tracker running in the background! That's right! the website is actually watching how you move your mouse. Unlike robots, humans tend to move the mouse cursor in random non-perfect patterns. This allows the website to distinguish with a very high precision, humans and computers. If this information wasn't enough already, as a second test, the website then quickly scans your browser cookies to check for any odd behaviour such as visiting the same site at the exact same time every single day. Now most of you are likely a bit disturbed by this invisible invasion of privacy...But as a whole you can thank CAPTHA for ensuring that you actually have a chance, however slim, of purchasing tickets to your favorite band online.

Bonus fun fact:

CAPTCHA stands for 'Completely Automated Public Turing test to tell Computers and Humans Apart'... And if that frustrates you anywhere as much as it does me, you are likely not a robot as well :)

Thanks for reading, I hope you enjoyed this article!

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Cheers!

-Kevin Manton