Skip to content



What is a CAPTCHA

On the Internet, forms are vital. We use it to subscribe to sites or newsletters, to post a message on forums,also to respond to a survey. On the whole, the usage of forms is to transmit information to the hosting server of the visited site. The latter uses these informations for various purposes. Therefore, it is to secure these forms that the CAPTCHA test has been implemented.

CAPTCHA stands for Completely Automated Turing Test To Tell Computers and Human Apart. As its name suggests, it makes it possible to distinguish whether a program or a robot or else a human is performing an action. It executes this through simple visual or auditory tests requiring recognition by humans. Its invention dates back to 2000 at Carnegie-Mellon University. In 2009, Google bought it under the reCAPTCHA name.

Why you need to use a CAPTCHA test?

Sending information through forms is a gateway for cyber attacks. This is because malicious code can be injected instead of real information in order to modify, for instance, the behavior of a part of the website. These are usually robots browsing the Internet for flaws that causes it. It is therefore necessary to make sure of the security of the forms when designing a website. The CAPTCHA does this very well. It integrates very well with HTML pages.

  • CAPTCHA protects programs that may make use of the functions of the form to generate spam emails. Including advertising, phishing or scam emails.
  • CAPTCHA prevents the creation of a plethora of fake accounts through robotic and automatic actions.
  • In the case of forums, CAPTCHA prevent sending a mass of spams.
  • It also blocks dictionary attacks aimed at cracking account login details.

What types of CAPTCHA are there?

The main use of a CAPTCHA to put the mind of the owner of a site at ease regarding the reliability of the information transmitted via the forms. However, a CAPTCHA placed after a form affects the visitor experience. Considering the case of a CAPTCHA to be resolved before finalizing an order in an online store. If CAPTCHA is difficult, it is obvious that many visitors can abandon their purchase. To resolve this problem and ensure security at the same time, CAPTCHA has had several versions since its creation.

  • The first version of CAPTCHA uses one or more distorted words on a degraded background to make computer interpretation difficult. The user must recognize the word, enter it in order to validate the form.
  • The 2nd version saw the light in 2009, named reCAPTCHA by Google. Here, the difficulty of recognition is increased by adding a trait. It is also possible to take an audio test.
  • The 3rd version arrise in 2014, is called reCAPTCHA v2 or No CAPTCHA reCAPTCHA. No more text to enter for this version. Now this is a box to be checked. Usually an additional step follows. This is one or more images from which you must select those corresponding to a given word.
  • Then in 2017, the 4th version arrives named Invisible reCaptcha. There are no more puzzles to solve or cases to tick, the distinction between human and robot is made on the basis of user behavior.