Who, what, why: What is replacing Google's annoying ReCaptcha test?

Online security checks asking users to type in random hard-to-read words are being replaced with a simple box to tick next to the words "I am not a robot". Why, asks Justin Parkinson.

It frustrates visitors to hundreds of thousands of websites. A computer presents users with a fuzzily written or confusingly presented word or two to type in.

Captcha, standing for Completely Automated Public Turing test to Tell Computers and Humans Apart, is designed to prevent automated spamming of sites by setting this test, which people find easier than machines.

Google's ReCaptcha system introduces hard-to-read text from newspapers, books and other old sources such as maps. It presents two words - one the computer recognises and one that it doesn't. That second word would have been scanned but rendered illegible and, so, the repeated deciphering of it by different users, who agree on what it is likely to be, would eventually enable that word to be reincorporated into the digitised archive it came from.