A
CAPTCHA (an acronym for "
Completely
Automated
Public
Turing test to tell
Computers and
Humans
Apart") is a type of challenge-response test used in computing to determine whether or not the user is human. This form of CAPTCHA requires that the user type the letters of a distorted image, sometimes with the addition of an obscured sequence of letters or digits that appears on the screen. Because the test is administered by a computer, in contrast to the standard Turing test that is administered by a human, a CAPTCHA is sometimes described as a reverse Turing test.
The Captcha can occur when you Train (usually before the super soldier medal), Work (usually before the hard worker medal) and voting.