CAPTCHA

08-04-2025

06:28 AM

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1 min read
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CAPTCHA is a crucial security tool to verify human users and protect websites from bots, but faces challenges.

About CAPTCHA

  • CAPTCHA stands for the Completely Automated Public Turing test to tell Computers and Humans Apart. 
  • The term “Turing test” is central to CAPTCHAs. 
    • A Turing test evaluates a computer’s capacity to simulate human behavior. 
    • In 1950, Alan Turing, an early pioneer of computing and artificial intelligence (AI), created the Turing test. 
    • A computer program “passes” the Turing test if its actions throughout the test cannot be distinguished from that of a person, i.e., if it behaves as a human would. 
    • A Turing test is not based on answering questions correctly; rather, it is concerned with how “human” the responses seem, irrespective of whether they are accurate.
  • CAPTCHAs are tools you can use to differentiate between real users and automated users, such as bots. 
  • CAPTCHAs provide challenges that are difficult for computers to perform but relatively easy for humans. 
  • For example, a CAPTCHA may ask the user to enter the characters displayed in a blurred image or identify all of the images in a grid that contain a traffic light. 
  • Some newer CAPTCHAs ask the user to click in a box stating that they are not a robot and use various metrics to differentiate between human and automated visitors.
  • CAPTCHAs are used by any website that wishes to restrict usage by bots.

CAPTCHA FAQs

Q1. What does CAPTCHA stand for?

Ans. Completely Automated Public Turing test to tell Computers and Humans Apart

Q2. What is the main purpose of CAPTCHA?

Ans. To distinguish humans from automated bots

Q3. CAPTCHAs are based on which fundamental computer science concept?

Ans. Turing test

Source: TH