What is a captcha? | reCAPTCHA | Why do websites ask [I am not a robot]
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Manas Sinha
Developer | Designer
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Manas Sinha
Developer | Designer

By Manas | 16 March 2021

Captcha

CAPTCHA stands for Completely Automated Public Turing test to tell Computers and Humans Apart. A CAPTCHA is a type of challenge-response test used in computing to determine whether or not the user is human.
You must have had a laugh when a website asked you to click on i am not a robot thinking that can’t a robot click it.
The captcha is not used to stop humanoid robots from accessing a website but to stop “bots”. These bots are just programmes/scripts thatare written to automatically visit the website. Why this automatic surfing is harmful? Since these are computers visiting the website they can do it very fast 1000s of times/second.
Let’s say you made a form to conduct a servey of how many students wants a exam to be cancelled. If there is no captcha one can write a code that can fill that form 1000s of time and therefore making the servey wrong. One can write a script to request a data from a website over and over very fast and that will result in delay in the response to legitimate clients or may be result in the server to crash.
Types of captcha:
  • Distorted text captcha image
  • Identify Objectsimage
  • Solve math equationsimage
  • I am not a robot | reCAPTCHAimage

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