{"id":997146,"date":"2020-05-20T07:50:00","date_gmt":"2020-05-19T23:50:00","guid":{"rendered":"https:\/\/geetests.com\/article\/what-is-captcha"},"modified":"2025-11-27T10:34:01","modified_gmt":"2025-11-27T02:34:01","slug":"what-is-captcha","status":"publish","type":"post","link":"\/en\/article\/what-is-captcha","title":{"rendered":"What is CAPTCHA? How it Works? | All You Need to Know!"},"content":{"rendered":"
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What is CAPTCHA?<\/strong><\/h2>\n

CAPTCHA is an acronym for <\/span>C<\/strong>ompletely <\/span>A<\/strong>utomated <\/span>P<\/strong>ublic <\/span>T<\/strong>uring test to tell <\/span>C<\/strong>omputers and <\/span>H<\/strong>umans <\/span>A<\/strong>part, which is a module used in websites, mobile apps, and APIs to distinguish automated computer programs from genuine human users.<\/span><\/p>\n

Sometimes, CAPTCHA is described as reverse Turing tests. As we know, the <\/span>Turing test<\/u><\/a> is a method of inquiry in artificial intelligence where a computer has to convince a human that it’s a human. Therefore a reverse Turing test is a human convincing a computer that it is not a computer. If you write a program that automatically generates such a test on the internet, then you get yourself a CAPTCHA.<\/span><\/p>\n

History of CAPTCHA<\/strong><\/h3>\n

The first commercial deployment of a CAPTCHA-like system<\/u><\/a> was done by Andrei Broder and his fellow engineers at the AltaVista search engine. They’ve developed an automated filter system to stop bots from submitting URLs (a type of black hat SEO) that skewed AltaVista’s algorithm.<\/span><\/p>\n

However, the term CAPTCHA was coined in 2003 by Luis von Ahn and his colleagues at Carnegie Mellon University in their publication <\/span>CAPTCHA: Using Hard AI Problems for Security.<\/u><\/a><\/p>\n

\"different<\/span><\/p>\n

For more information, please refer to “<\/span>History of CAPTCHA – The Origin Story<\/u><\/a>“.<\/span><\/p>\n

How Does CAPTCHA Work?<\/strong><\/h2>\n

CAPTCHAs are deployed at operational gateways such as login, register, submit, etc., to prevent computer programs from accessing and committing fraud and abuse.<\/span><\/p>\n

The original idea behind CAPTCHA is to present cognitive challenges in the form of distorted texts that humans can recognize and pass easily while computer programs cannot.<\/span><\/p>\n

\"obsolete<\/span><\/p>\n

However, with the advancement of computer technologies, traditional CAPTCHAs quickly became obsolete. Today, advanced CAPTCHA modules use risk analysis engines based on behavioral detection and artificial intelligence technologies to prevent sophisticated bot threats.<\/span><\/p>\n

What are CAPTCHAs used for?<\/strong><\/h2>\n

Digital criminals use bot programs to commit fraud and abuse through automation of tasks in a malicious way such as credential stuffing attacks, email or comment spam, online poll fraud, etc. CAPTCHA prevents digital criminals from automating their fraudulent tasks by ensuring there is a real human behind each request, thus effectively preventing scammers from scaling their illicit operations and committing online fraud and abuse.<\/span><\/p>\n

CAPTCHA prevents threats including:<\/span><\/p>\n