A request that this article title be changed to Captcha is under discussion. Please do not move this article until the discussion is closed. |
This article may need to be rewritten to comply with Wikipedia's quality standards, as It feels like an essay criticising CAPTCHA. (November 2022) |
A captcha (/ˈkæp.tʃə/ KAP-chə, originally the acronym CAPTCHA)[1][2][3][4] is a type of challenge–response test used in computing to determine whether the user is human in order to deter bot attacks and spam.[5]
The term was coined in 2003 by Luis von Ahn, Manuel Blum, Nicholas J. Hopper, and John Langford.[6] It is a contrived acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart."[7] A historically common type of CAPTCHA (displayed as reCAPTCHA v1) was first invented in 1997 by two groups working in parallel. This form of CAPTCHA requires entering a sequence of letters or numbers in a distorted image. Because the test is administered by a computer, in contrast to the standard Turing test that is administered by a human, CAPTCHAs are sometimes described as reverse Turing tests.[8]
Two widely used CAPTCHA services are Google's reCAPTCHA[9][10] and the independent hCaptcha.[11][12] It takes the average person approximately 10 seconds to solve a typical CAPTCHA.[13]
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was invoked but never defined (see the help page).CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) is a [...]