What is CAPTCHA | Types of CAPTCHA | Why is the CAPTCHA code used | How CAPTCHA Works

You must have seen many times that whenever you create an ID on a website, log in or recover a password, you definitely encounter Captcha. Where you have to fill the box below by looking at the numbers or laters in the given image or select the image according to the question asked. You must have thought many times what captcha is and why it is needed. What are the work of CAPTCHA and many other questions will definitely come in your mind? Today you will get all the information related to CAPTCHA through this article.

What is CAPTCHA? 

The meaning of captcha is a  kind of device with the assistance of a computer program to watch that the info that is giving is human or machine. 
Full-Form of Captcha is "Completely Automated Public Turing Test to Tell Computers and Humans Apart". The Captcha Code was first made in 2000 and was first utilized by Yahoo Company. 
So for your data, let us reveal to you that Captcha Code Number was made in light of the fact that at one time hackers utilized Spam to make traffic on their site. Due to which a connection to your site could be sent by remarking on any blog. So annoyed with this, this incredible method was received.

Why is the CAPTCHA code used?

CAPTCHA prevents spam in site comment areas and on web journals. Many spammers spam comment sections with links to increase search engine rankings. The test ensures just humans comment and users don't need to sign in previously to leave a comment. 
Numerous companies offer free email benefits however a while ago bots would pursue many free records and afterward utilize these records to cause devastation on the Internet. Presently individuals need to finish a CAPTCHA before having the option to get a free email account. Free administrations ought to be secured by a CAPTCHA to forestall misuse by means of automated content. 
It offers protection from scrapers who need to duplicate the email addresses of users. Spammers would crawl the Web for email addresses that are posted in cleartext. By using CAPTCHA you can secure against these scrapers. People need to solve a CAPTCHA before an email address is shown.
In some cases, individuals don't need a website page to appear so there is an HTML label that conceals the page from robots. Big search engine companies respect this but sometimes it doesn’t prevent all bots from coming through. This is the thing that CAPTCHA helps to prevent.
Frequently people will utilize programs to stuff online surveys for a specific vote. Generally, IP addresses are recorded to keep people from voting more than once yet with the utilization of bots one can go around this arrangement. This makes it hard to genuinely trust online surveys if CAPTCHA codes are not included. 
Dictionary attacks are when a computer goes through every word in a dictionary in order to obtain access to someone’s password and account. CAPTCHAs prevent this by requiring the computer (or person) to enter a code after a specific measure of ineffective logins. 
The prevention of torrent sites from bots falsifying seed counts and positive reviews in order to trick people into download a trojan virus.

How does CAPTCHA work?

Classic CAPTCHAs, which are as yet being used on some web properties today, include requesting that users recognize letters.  The letters are distorted so that bots are not likely to be able to identify them. To pass the test, users need to interpret the distorted text, type the right letters into a structure field and submit the structure. In the event that the letters don't coordinate, users are prompted to try again. Such tests are normal in login structures, account signup forms, online polls, and internet business checkout pages. 
The idea is that a computer program, for example, a bot will be not able to interpret the distorted letters, while a human being, who is accustomed to seeing and interpreting letters in a wide range of settings – various fonts, various handwritings, and so forth – will, for the most part, have the option to distinguish them. 
The best that numerous bots will have the option to do is input some irregular letters, making it statistically unlikely that they will pass the test. Thus, bots fail the test and are blocked from interacting with the website or application, while humans are able to continue using it like normal.
Advanced bots can utilize machine figuring out how to identify these distorted letters, so these sorts of CAPTCHA tests are being supplanted with more mind-boggling tests. Google reCAPTCHA has built up various different tests to sift through human users from bots.

Types of Captcha

1. The standard word CAPTCHA with an audio option

This is the standard captcha available whenever a security check-in is required, where you need to write the word which has been displayed. But some of the distorted word images are hard to solve. To get this pass through it allows you to use the option of “Recaptcha”, in order to receive a new one.  There is also an audio option if you are unable to visually make out the word. These are the most commonly used while preparing a form in website development or app development.

2. Picture identification of CAPTCHA

This captcha provides users for selecting the elementary choice of selecting the correct image that they are asked to identify. This type of captcha usually never gets harder than the basic images, so you do not have to worry about your users not being able to depict them.

3. Math Solution CAPTCHA

This type of captcha involves basic math problems and if your user cannot solve these basic questions then probably you do not want them to visit your website further. This provides with easy to read numbers and must be solved to get through the captcha.


These type of captchas are called “Super Captcha” because there are several 3D images which include both images and words and thus become hard for one to solve it.

5. Ad-injected CAPTCHA

This type of captcha helps your websites to earn some extra cash by publishing it, which in turn also helps in terms of brand recognition.

6. Query slider CAPTCHA

This is a plugin that gives you the ability to add captcha to your forms which are easy to use. This plugin is very useful to keep the spammers away. This plugin lock is disabled until a person slides it to enable it.

7. Drag and drop CAPTCHA

This is also one of the easy to use captchas. It is jQuery based which allows users to drag the required object or shape to pass through the security gate.

8. Tic Tac Toe CAPTCHA

This captcha which involves gamification was designed for fun and an easy way to ensure that only humans can interact with your website. The captcha does not hurt that much.

What is reCAPTCHA?

reCAPTCHA is a free service from Google that helps protect websites from spam and abuse. A “CAPTCHA” is a Turing test to tell humans and bots apart. It is easy for humans to solve, but hard for “bots” and other malicious software to figure out. By adding reCAPTCHA to a site, you can block automated software while helping your welcome users to enter with ease.

CAPTCHA Advantages and Disadvantages

Captcha is a way to differentiate between an automated computer program and a human. It is a box with distorted text that must be deciphered in order to enter free email services, online polls, and to complete online purchases.


-Recognizes a human and a machine 
-Makes online surveys more genuine 
-Reduces spam and viruses
-Makes internet shopping more secure 
-Diminishes abuse of free email account services


-Sometimes very difficult to read
-Are not perfect for users with disabilities 
-Time-consuming to decode 
-Specialized troubles with certain web programs 
-May incredibly improve Man-made reasoning

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