CAPTCHAs: What are They?

Feb 17, 2020

You have certainly come across specific statements like “I’m not a robot” on webpages, especially in comments sections. You’ll have to type in your comments and then click on the tab “I’m not a robot” to post your comment. Such a tab is called CAPTCHA.

A CAPTCHA has many forms. Some of them are simple operational arithmetic where one has to solve a problem to make a comment live. But the common ones mainly include a word or a set of letters made into a word (that might not bear any specific meaning) that you’ll have to copy and type into the box provided below the CAPTCHA tab. You’ll then have to click on “submit/send/OK” to complete the procedure.

A few example CAPTCHAS are provided below.

Arithmetic CAPTCHA



CAPTCHA’s the acronym of “Completely Automated Public Turing Test.” This test is mainly done to distinguish between computers and humans. So you can see that CAPATCHAs are basically designed to ascertain whether the user’s a human or a machine. The first CAPTCHA was designed in 1997 consisting of a set of obscured letters like the one shown below:

Obscured CAPTCHA  

Why are CAPTCHAs used?

CAPTCHAs are mainly used for security purposes, to block various spam activities as well as bots that attempt to sign up automatically on several websites or attempt to harvest several e-mail addresses at random. Such automated responses are blocked by CAPTCHAs because they normally cannot comprehend such distorted letters.

An important point to remember: The CAPTCHA algorithm is open to all. It’ suggested in its name itself (p->Public).


CAPTCHAs involve the user in various tasks. These tasks might include tasks like reading, copying and uploading the displayed text in the indicated space or it might involve several tasks relying wholly on visual perception.

CAPTCHAs aren’t only typing oriented. Speech recognition software and audio interpretation of text are also used as a form of CAPTCHA. These are particularly suitable for visual impaired people.

CAPTCHA problems

The first problem that we are going to mention is the most obvious of the lot- Time. Many people find these CAPTCHAs pretty annoying especially due to the time is taken to solve such CAPTCHAs, however, small it might appear to be. They consider this an unnecessary waste of their time. We feel that their claim’s neither justified not it is unjustified because CAPTCHAs are definitely a waste of time (even a waste of 5 seconds is considerable if you think of it in a collective sense) but then it is also a security measure against spam and bot activities.

Another problem with CAPTCHAs is that the tests sometimes go beyond the scope of comprehensibility. The distorted images or the letters go beyond the scope of understanding of many people. Now this point is completely valid, and we agree that these things do happen with CAPTCHAs. Visually impaired people face a whole lot of problems with CAPTCHAs due to this exact reason. Sometimes, the auditory ones also fail to live up to the mark because of the presence of distortions/noise. Thus, this problem definitely needs a solution as soon as possible.

The main goal of CAPTCHAs is to stop automated responses and spam related activities. These days, the efficiency of CAPTCHAs is under a big question mark. Modern bots have found various ways to bypass CAPTCHA security measures resulting in several spam-related activities. This, the goal of complete security against spam and automated response is seldom fulfilled.

You might always have been annoyed at the times you encountered a CAPTCHA, especially when the time was of the essence. You had also wondered as to why you had to fill up those annoying letters in a blank space provided below to fill up an application form or something similar. Now that you know what CAPTCHAs are, what do you reckon? Are they more of a problem and less of a solution or the vice versa? The decision rests with you.

Article Posted in: Academics

Sudipto Das

Sudipto writes educational content periodically for MyPrivateTutor Singapore and backs it up with extensive research and relevant examples. He's an avid reader and a tech enthusiast at the same time with a little bit of “Arsenal Football Club” thrown in as well. He's got more than 5 years of experience in digital marketing, SEO and graphic designing.

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