What is CAPTCHA and How it Works?

CAPTCHA, or Captcha (pronounced cap-ch-uh), stands for “Completely Automated Public Turing Test to Tell Computers and People Apart” and is a form of challenge-response test that ensures that the response is generated entirely by humans and not by a computer.

In layman’s terms, it’s the word verification test that appears at the bottom of a sign-up form when you join up for a Gmail or Yahoo account. The following graphic depicts typical CAPTCHA samples.

Captcha Sample

Almost every Internet user will come across CAPTCHA in their everyday browsing, but only a handful understand what it is and why it is utilised. So, in this piece, you’ll learn everything there is to know about CAPTCHA and why it’s utilised. What exactly is the purpose of CAPTCHA?

CAPTCHA is primarily used to prevent automated software (bots) from acting in the place of real people. For example, when creating a new email account, you will be presented with a CAPTCHA at the end of the sign-up form to confirm that the form is filled out by a human and not by automated software or a computer bot.

CAPTCHA’s major purpose is to provide a test that is simple and straightforward for a human to answer, but nearly impossible for a computer to solve.

What is the Need to Create a Turing Test?

The CAPTCHA may appear foolish and inconvenient to many people! CAPTCHA, in reality, has the capacity to safeguard systems against harmful attacks in which people attempt to cheat the system. Attackers can employ automated software to generate a large number of requests, putting a lot of strain on the target server.

This could result in a reduction in the quality of service provided by a system, either as a result of misuse or a waste of resources. This might have a significant impact on millions of legitimate users and their requests. CAPTCHAs can be used to defend systems that are vulnerable to email spam, such as Gmail, Yahoo, and Hotmail services.

Who Uses CAPTCHA?

Websites that provide services such as online polls and registration forms commonly use CAPTCHAs. Web-based email services such as Gmail, Yahoo, and Hotmail, for example, provide free email accounts to their subscribers. CAPTCHAs are used during the sign-up process to prevent spammers from utilising a bot to create hundreds of spam mail accounts.

Designing a CAPTCHA System:

CAPTCHAs are designed in such a way that computers lack the ability to process visual information in the same way that humans do. People can look at a picture and choose examples much more successfully than they can with a computer.

This is due to the fact that computers lack the natural intuition that individuals possess.
CAPTCHAs are activated by showing clients a picture with misshaped or hastily extended characters that only a few individuals should be able to recognise.

Characters are sometimes exaggerated or given a raucous foundation to make it more difficult for PCs to understand the examples. The majority of CAPTCHAs, although not all, rely on a visual test. A few websites use an unusual CAPTCHA framework to differentiate between people and computers.

For example, a client is offered four photographs, three of which are of critters and one of which is of a blossom. A request is issued to the client to select only those images that include animals. This Turing test can surely be completed by any human, but it is almost impossible for a computer to complete.

Breaking the CAPTCHA

Breaking the CAPTCHA is a difficult endeavour that requires training a machine how to interpret information in a way that is similar to how people think. When it comes to recognising the patterns in CAPTCHA images, algorithms with artificial intelligence (AI) will have to be devised in order to make the machine think like humans.

There is, however, no universal algorithm that can bypass and defeat any CAPTCHA system. As a result, each CAPTCHA algorithm must be treated separately. It may not work 100% of the time, but it can work frequently enough to be useful to spammers.