Captcha those spammers

Last year, we were trying to find a way to stop people from sending spam through our website. At the time we had no idea that we were actually implementing a “captcha”.

“Captcha” - Completely Automated Public Test to tell Computers and Humans Apart.

This is often implemented by rendering a word in an irregular, distorted way against a distracting background and asking the user to type it in. Failure to type in the correct word means that the form submission is rejected. It’s very, very difficult to automate that word recognition so we’re safe for a while. (Unless some spammer happens to advance the field of character recognition.)

Lots of websites do this especially ones that involve posting messages or signing up for email. The first site I noticed doing this was the Yahoo email service.

Here are some interesting references: