To ensure real folks are using resources, rather than a malcious program, CAPTCHA controls continue to become more complex and may even challenge users with math problems.  This is to keep automated spam agents from joining email or forum groups.  As the article notes, this is also challenging for users to invoke these resources.

The CAPTCHA system was invented around 2000 by a team of researchers at Carnegie Mellon University in Pittsburgh. The team came up with the CAPTCHA acronym, which stands for “Completely Automated Public Turing Test to Tell Computers and Humans Apart.” (It’s not a perfect acronym.)   According to the Carnegie Mellon website, the first CAPTCHAs were developed for Yahoo to prevent automated programs from rapidly setting up free email accounts, which would in turn be used to pump out spam.

Then I was confronted with a “CAPTCHA” — one of those hard-to-read, squiggly collection of letters and numbers that ensure you’re a real person and not a “bot” trying to game the system.  “To tell you the truth, they are getting harder to read, even for me, but the ‘bots’ that leave spam on your site are getting better at recognizing the CAPTCHAs as well,” Lyons said.  “When we first started using them, a functional CAPTCHA just used a couple of funny fonts and some lines through the text to make it hard for machines to read. Then the bots got smarter, and [now] we are all struggling with reading the CAPTCHAs.”