CAPTCHA (Challenge-response test)

found: Work cat.: Yan, J., El Ahmad, A. S. A low-cost attack on a Microsoft CAPTCHA, 2008:p. 1 (CAPTCHA (Completely Automated Public Turing Test to Tell Computers and Humans Apart); a program that generates and grades tests that are human solvable, but intends to be beyond the capabilities of current computer programs; a standard security mechanism for defending against undesirable or malicious Internet bot programs)

found: CAPTCHA website, Apr. 6, 2009(CAPTCHA is a program that protects websites against bots by generating and grading tests that humans can pass but current computer programs cannot. For example, humans can read distorted text ... but current computer programs can't)

found: Wikipedia, Mar. 27, 2009(CAPTCHA or Captcha; contrived acronym for Completely Automated Public Turing test to tell Computers and Humans Apart; a type of challenge-response test used in computing to ensure that the response is not generated by a computer; sometimes described as a reverse Turing test, because it is administered by a machine and targeted to a human, in contrast to the standard Turing test that is typically administered by a human and targeted to a machine)