What is reCAPTCHA? Definition

ReCAPTCHA is a commonly used method of website protection against spamming bot activity.

It is a free human verification system that protects the website from various types of abuse.

How Does reCAPTCHA Work?

ReCAPTCHA is a product of Google and so far there have been 3 versions of this service released. The first one stopped functioning in 2018. The other two are still being used and improved.


The reCAPTCHA v2 widget provides the image recognition test. Users need to identify images that contain particular objects, such as animals, trees, road signs or bridges. Often objects should be chosen out of blurred images, however, this is possible as people are used to perceiving objects in various contexts and situations.

As millions of users identify illegible text and select objects on blurred images, the data is entered into AI systems to develop machine learning. ReCAPTCHA uses solutions for image annotation and data sets for teaching intelligent machines.


ReCAPTCHA v3 uses an advanced risk analysis algorithm which considers the amount of time needed to enter data in the forms. To prevent from being hacked, Google doesn’t provide much detail about how the algorithm works. It is recommended to use the reCAPTCHA v3 service on several pages, not just to register or log in. Based on specific interactions of users with the website, it is possible to better assess whether the actions represent human or bot activity.

Get a free quote

SEO SEM Agency based in Europe