What is CAPTCHA? How does it work?


When we have  entered the details in any form, we saw a captcha there. It is there for security purpose. The main aim is to determine whether the person who is accessing the data is human or robot. In this article, we will discuss what is captcha and how does it work?

So read on the full article to know what is captcha and how does it work.

What is CAPTCHA ?

CAPTCHA stands for Completely Automated Public Turing test to tell Computers and Humans Apart. CAPTCHA is used to conclude that whether the user is a human being or a spam BOT.

CAPTCHAs control or manipulate numbers and letters, and it depends on the ability to think of a human to find or determine what kind of a response humans give & which symbols they are.

CaptchaCAPTCHAs played an important role because they are designed to block activities from automated bots. CAPTCHAs are themselves automated. In some websites, Captcha’s are programmed to pop up in certain places, and they automatically fail or pass users.

Where We Found Captcha ?

When entering debit card or credit card information on websites, you might be asked to copy a series of words or a math sum to continue. While usually, this is a quick step before you can continue your activity, many people wonder what a CAPTCHA is? And what is its purpose?

On a web page or a website when we want to enter our debit card or credit card detail, we might be asked to copy a series of words including alphabet, (either in small or capital letters), numbers. Mostly it is a quick stop before we continue our activity. At that time most people thought What a CAPTCHA is? and what is its Purpose.

Purpose of CAPTCHA 

Nowadays with the advancement in technology, hackers also become the most clever ones. to stop activities from robotic sides, here CAPTCHA plays a significant role.

The captcha which is used in web pages asks the user to verify the captcha letters or image which include alphabet or numbers. Here the letters are not in a serial manner or distorted. so the activist or bots are not able to find an incorrect way. so BOTs were unable to pass the CAPTCHA test.

Actual User may only be able to pass the CAPTCHA test and able to interpret the distorted text, and able to type in a correct manner and submit the form. Users have an option to pass again if the letters don’t match. we have seen almost such tests are common in account signup forms, doing online transactions or submitting online login forms, etc.

Also check: Improve Website security

How does Captcha work?

The captcha was designed only to support the security of the website.

Working of Captcha

  1. Earlier a few years back, Alan Turing has designed a game. In the game, he adds interrogator and participant, where the interrogator has to ask the questions and the participant has to answer it. Machines and human works as participants. The role of the interrogator was confined to response only. In case if the interrogator gives wrong judgment then the machine has chosen the Turing test.
  2. Similarly, the captcha role is to ask a similar way so that computers are unable to handle that. But do you know what? Humans can easily answer that.
  3. Here in this, you have to perform some relevant actions and then you ought to pass the captcha test.
  4. The popular type of test is by using image testing. Here distorted letters are there. The main benefit is human has high thinking capability but the computer or bots can’t possess this way of thinking.
  5. Humans having a great tendency to process data which is in visual form but on the other hand, computers lack this visualization skill.
  6. Humans possess pattern visualization(pareidolia) whereas machines can’t have those provisions.
  7. Computers only know the value of 0 and 1, but humans can know more than that.
  8. So many creators are deploying different sophisticated algorithms for generating distorted texts randomly.
  9. These are harder to solve by computers or bots.

Also check: What is Cyber Security


I hope you have enjoyed the article. In this article we have discussed all about captcha that is What is captcha and how it works. If you are still facing any doubt, ask me freely in the comment box.


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Palvi Soni is a technical content writer and researcher. She is here to explore her best skills and impart relevant knowledge to the readers. She loves to write on different niches like career, education, data science, and digital marketing.


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