You have noticed that when you go to some website or service online then a strange box comes in front of you which had images in the form of blocks and asks you to check the boxes with specific images. When you do the job accurately it allows you to enter the website. And yes before entering the website you have to also check the “I am not a robot” box.

This is known as CAPTCHA. CAPTCHA stands for “Completely Automated Public Turing Test To Tell Computer and Humans Apart“. This test is mostly made to differentiate between humans and robots (software or hardware) and prevents the bots to enter the website.

This thing is made to prevent spam and many other things. For example, if a website has the email subscription option and a lot of bots go there at the moment and start giving the emails randomly. These bots will also give the emails that do not exist yet. At a moment thousands of mail will be made.

This cause a much problem for the owner of the website giving services to different people. The owner of the business cannot be able to determine that which is the correct email asking for help and which is not a good email asking for help.

Other things like if you have the website giving different types of services then at a moment thousands of bots come into your website. This can cause a server error on the website. Other than that if someone is giving a service and you have to signup before using the service.

You make an account and start using the service but if the bots will come there and they started to make several accounts in a moment then it will create issues for the owner. This is the main reason behind preventing these types of bots.

The CAPTCHA may be in the form of an image or text. So, the question that arises is that why robots cannot read CAPTCHA. Let’s discuss it in detail.

Why Robots Can’t Read The Captcha?

We mostly see two types of CAPTCHA. One is in the form of text and one is in the form of an image. Text test was introduced first to prevent boats from coming to the website. It was introduced because the computer was unable to identify the text in the form of an image.

After all, it analyzes the image scanning its pixels and if we change the structure of the word then the computer will not understand it easily.

A few years back if you give the computer a book to scan then there will be some words that cannot be understandable by this technology. In today’s world also you can see that if you wanted to scan a document with the help of a computer then some words will be not processed by the machine.


So, at that time when people wanted to send bots on different websites then they have to write the very random words with random structure just shown in the above image. Bots cannot do it because it is easy for the human with the brain to solve it but not for a robot or the software.

In this way, the bots were prevented from entering the website. But there was a problem with this type of CAPTCHA. They were time-consuming and a lot of users become angry to fill it again and gain. If a person will be coming for the important task and he will waste much of time on it then it is bad.

This makes the experience bad. If you know Google then you should also know that its priority is the users which are consuming data on search engines. So, Google will not bear that their users become angry due to service.

One other problem with this type of CAPTCHA was that the bots were becoming more intelligent by using the technologies like artificial intelligence and machine learning so there was an issue if any robot can pass these types of tests and enter the website.

Then Google came with reCAPTCHA which we are currently using while entering into many sites. This is very fast compared to the text. In this CAPTCHA different images are shown to you and ask the user to detect the specific object.

It will be easy for humans and very difficult for bots. Because Google determines that the user is a bot or a human by its previous searches on the search engine, its IP address, and also the speed of moving the mouse with machine learning algorithms.

If a human will detect the object then it will immediately click on it but a robot will first analyze the whole thing and then detect the first image after that very slowly it will detect the second image that the third and check the box.

The system will easily analyze what the bot wanted to enter into the website. This type of CAPTCHA asks the questions like “select the car given in the image“. So, in the image, there will be trucks, busses and many other things also. A human will easily analyze the car and check the box but a robot cannot analyze the difference so quickly.

First, the robot has to analyze what is the system saying in the question then it will process the image and then it will check images after the time gap. During this, the system will be able to analyze it.

The other thing is that the images are made so relevant and low quality that sometimes we humans also cannot pass it but after two or three attempts we can solve it but a robot cannot because things will be relevant and it will not know which is correct.

So, there were two types of CAPTCHA and why robots cannot read them. Mostly we are using CAPTCHA in the form of image and text form is old now and many bots can pass it easily.

If you had any questions related to this then you can comment below.


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