What is CAPTCHA And What Are Its Types

CAPTCHA basically is an acronym for Completely Automated Public It’s a turing test to tell Computers and Humans apart.

CAPTCHA is called Completely Automated Public Turing Test. It is a tool that websites use to differentiate humans from bots.

CAPTCHAs are the internet tools to differentiate between real users and automated robots. Whenever a computer system detects an unidentified activity, it won’t proceed further until you fill the CAPTCHA. These challenges include unique codes, puzzles, identifying a stretched letter or numbers, clicking in a particular area or image.

Since they are simple to perform by humans but not for bots, systems find out about the user identity being genuine or automated.

What Are The Types of CAPTCHA?

Computers have categorized the CAPTCHAs into three main types.

  • Text CAPTCHAs
  • Image CAPTCHAs
  • Audio CAPTCHAs

What are Text CAPTCHAs?

Text-based CAPTCHAs are used as a primary source to identify humans. Text-based CAPTCHA is designed to identify the viewer with random words, phrases, letters, and digits. If it is a human being, they know how to attempt the CAPTCHA. If its a bot, they do not.

Some of the text-based CAPTCHAs show uppercase and lowercase letters to make it difficult if an automated system is trying to get in.

However, some CAPTCHAs are designed to represent the characters in a detached way that would take a human brain to solve. The interpretation of the distorting characters, alphabets, images, animation, and scaling takes minutes to resolve. Moreover, this type also shows overlapping characters in diverse fonts along with graphics. Sounds, background pollution, colors, arcs, dots, and types of lines.

The detachment is a protected way to restrict the Bots to circumvent the procedure. On the contrary, it becomes strenuous for human beings to interpret since there are insufficient text recognition involvement algorithms.

What are Image CAPTCHAs?

Image-based CAPTCHAs are another type of CAPTCHAs that provide an alternative to text-based ones. It includes graphical elements that a user can recognize and identify, such as images of animals or objects.

However, these tools can create a hassle for visually disabled users to interpret. For instance, if a Bot is trying to access the web browser, it would create difficulty for it to interpret the image along with the rhetorical classification.

What are Audio CAPTCHAs?

Audio CAPTCHAs were designed for visually enabled users to provide them with the audio in the form of alphabets and numbers they are mandatory to re-enter after being heard by a user. These CAPTCHAs are provided along with the text and numerical arrangements.

Therefore, audio CAPTCHAs are difficult to use for humans as well as for robots since they are demanding to distinguish from the background audio noise since it is overwhelming to recognize the sentence or letters accordingly.

What is the usage of CAPTCHA?

The purpose of the usage of CAPTCHA is to recognize the internet traffic’s identity whether it’s a bot or human. To prevent the numerous attempts of automated systems (bots) to enter your network through different web browsers, web admins use CAPTCHA. There are several benefits of using CAPTCHA that businesses and organizations are strictly following it.

Any website that is determined to restrict the Bots from invading their network, prioritize using CAPTCHAs to prevent the scenario. There are multiple uses of CAPTCHA but these are the enumerated ones.  Let’s get acquainted with some of them.

  • Accurate Polls: CAPTCHAs take care of the poll distortion by ensuring that the website has only human votes through human traffic. Nevertheless, it cannot limit the entire number of votes since it needs a certain time for processing every collected vote.
  • Limited Registration: Bots can spam registration portals by creating fake accounts. Sending CAPTCHAs can save the situation by restricting the machines to create uncountable accounts along with preventing the resources that would have got wasted if not protected by CAPTCHAs.
  • Restricting Ticket Inflation: It can be implemented to restrict people from spreading inaccurate news about several events. Also, it can keep ticket dealers under control to buy and sell massive amounts of air tickets.
  • Restricting Hate Comments on Web Pages: Sometimes people generate bots in forms to spread hate speech, online harassment, inaccurate information about certain people. CAPTCHAs could be a huge help to restrict these spam activities since a bot cannot attempt it accordingly and by failing the CAPTCHAs block their access to such sites.

How Does CAPTCHA Work?

CAPTCHAs work as the primary technique to recognize between humans and web bots, to provide a piece of information to the user for interpretation. CAPTCHAs are basically designed to secure the networks against bots.

Previously, computers send overlapping letters and disfigured numbers to users to test their capability. Of course, humans are intellects and robots are machines that are designed by humans to act a certain way and perform a specific task.

When receiving a CAPTCHA, a system asks for answers as verification. Human beings can easily recognize and get done with the task. In contrast, robots are not able to do that efficiently since the provided misinterpreted letters and distorted numbers make it impossible for them to attempt the task correctly since a wrong entry wouldn’t be allowed.

The CAPTCHA types are designed as per human creativity and capability to get along with the puzzling formats of assembling letters and numbers. On the contrary, CAPTCHAs are not the cup of tea for bots since they have limited intelligence.

In the scenario, bots can only perform if given set patterns or input haphazard characters. The limitation has been made it impossible for the bots to act accurately.

More difficult CAPTCHA was introduced to detect robots after the emergence of machine learning, also known as AI (Artificial Intelligence). Bots have become smarter over time, so the complexity of CAPTCHAs needs to match the growing intelligence of bots.

Drawbacks of CAPTCHA

CAPTCHAs are really impactful but there are some undeniable drawbacks too. They are mostly involved in the act of restricting bots to enter any valid websites and create an unwanted situation. On the contrary, they are counteractive to the user experience for these reasons:

  • Several CAPTCHA types do not support every browser.
  • Some of them are not visible to the actual users who use a website entering assistive readers or screen devices.
  • Based upon the kind of CAPTCHA, some of them are hard to get and this creates a hassle for many of the users (humans).
  • People get irritated by filling out CAPTCHAs.


ReCAPTCHA is run by Google to validate legit users. The “I am not a robot” verification box gives. A human being needs to click it to continue with the web activity. As compared to text, image, audio, and video CAPTCHA, these types of CAPTCHAs are quite simple to use.

If it detects an error, it would provide from the types of image CAPTCHA to continue the user activity. Google makes ReCAPTCHA difficult for IP addresses that show unusual activity.

Wrapping Up

CAPTCHAs are playing their role in virtual safety but still, it comes with pros and cons. Creating CAPTCHAs for every website would be a help to reduce severe cases of scams. There is overwhelming traffic on the internet that is not genuine and operated by systems in the form of robots.

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