What are CAPTCHAs ???? | HOW they WORK ? | How they differentiate between HUMANS and ROBOTS ?

On the internet, you must have come across captchas where you are asked to arrange and write certain letters in the correct order to make a meaningful word or sometimes simply write the word you are asked to in a specific place where the word is generally arranged in a unique way rather than in a straight way.

These captchas are very useful. They are of various types out of which we discussed two of them above. Another type is the one where you just need to click on a box adjacent to which it's written
I AM NOT A ROBOT and does the same work what the other captchas do.

Let's not talk much about how it looks since we all have seen them on various websites mainly when we sign up or make an account on a website for example in Gmail, Book a Railway ticket, etc.

But, have you ever thought why they are there or why it asks us to write a jumbled word in the correct order or write something which is already written, once again. You might find it really irritating and time-consuming but let me tell you, it's a very important part of a website that helps the website owner as well as its users. So read till the end because you are going to get some information about a very interesting topic.

Now to understand it in a simpler way, you can take an example of booking a railway ticket. Now you must have heard the name IRCTC website from where you can book railway tickets online. You must have seen the concept of Tatkal ticket by which you can book a reservation ticket even before a day of your travel. Generally, a particular time is allotted when the Tatkal opens and a user can come to the website to book a Tatkal ticket. The important fact is that these Tatkal tickets are limited and you can consider it as a flash sale where you have to be very quick. Now in general, a user takes a minimum of three to four minutes to fill his/her details, choose the train and finally book a ticket.


Now here the question arises, what if someone who's a coder, makes a script/ a bot to do all these i.e. to fill details, find trains, check availability and book train then he/she can do all these in 10 to 15 seconds with the help of the script and now because of this, other users will not get the opportunity to book Tatkal tickets.

Not only in Railway ticket booking but various other website owners were trying to find out some way out of this as this could destroy their website with spam registrations and then finally the concept of Captchas came which proved to be a very good solution for this problem and to prevent SPAMS. Website owners started using this on their websites and it became very popular. The older kind of captchas generally dealt with numbers.
                          
These captchas consisted of numbers arranged in an improper manner, with noise at the background and altogether which were not understandable by a computer and these captchas asked the human user to arrange those given numbers in the proper way to make it meaningful and if it was not fulfilled, you were not allowed go to the further steps. This created a difference and it failed the work of the scripts. These captchas helped in finding out a difference between a computer and a robot.

Later the company Re-captcha came that focused on making captchas that would ask the users to rewrite a jumbled word in the proper way instead of showing some random digits. They scanned several books through the OCR technology and found out the words that the computer was unable to identify. They choose those words to make the captchas.

Later in 2009 Google bought the company Re-captcha and focused on the further development of the concept of captchas and later google designed special captchas which only asked the user to click on a box adjacent to which it's written I AM NOT A ROBOT as discussed above.

                                   
Now at present these captchas are used on various websites and is helping the website and preventing it from fraud and spams. These captchas contain such contents which are only understood by a human and not by any computer which prevents any script functions.

So this was how captchas work, so if you liked the content then do not forget to share it with your friends and make them also know about this. Also, you can follow me on my social media accounts (link in the right sidebar).