What is captcha? and how to write a captcha code ?

What is captcha?

 What is Captcha – The full name of CAPTCHA is “Completely Automated Public Turing test to tell Computers and Humans Apart”.

 CAPTCHAs are a tool you can use to differentiate between real users and automated users, such as bots.  CAPTCHAs provide challenges that are difficult for computers but relatively easy for humans.

How to write captcha code –

 To enter the captcha code, you have to type the given letters or numbers in a message or a small box.  This security system protects the website from Bots and Spammers.

 Some Captcha codes are hard-typed, requiring you to type letters or numbers from a message.  You can see this code at the bottom of the web page or on the login form.

 Other Captcha codes differ, requiring you to type a number or a word referencing a pair of pictures.  For this, along with the given image, you will also see the written text, which you will have to type.

 Finally, some captcha codes are available in audio or video files, after listening to which you need to type a certain sentence or word.

 Features of captcha –

  • Captcha is difficult to crack and the algorithm that operates it is patented.  However, it was made public because Captcha is not just a new algorithm but a difficult case of artificial intelligence.  Therefore, reverse engineering is challenging.
  • Deciphering a CAPTCHA requires three primary abilities.  When the following capabilities are used in sync, it becomes difficult to decrypt the CAPTCHA.  These three capabilities are as follows:-
  • Continuous Image Recognition Ability: No matter what shape the alphabet appears in, the human brain can automatically identify the characters.
  • Image segmentation ability: This is the ability to separate one character from another.

How captchas work –

 Quite simply, Captcha works by asking end users to perform certain tasks that a software bot cannot do.  If the user can perform the task correctly, it provides authentication to the service that the user is a human and not a spambot and allows the user to continue.  Allows

 Tests often involve JPEG or GIF images because while bots can identify the existence of an image by reading the source code, they cannot tell what the image represents.

 Because some CAPTCHA images are difficult to interpret, human users are usually given the option to request a new CAPTCHA test.

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