You must have encountered with one or both of the images above. It is a CAPTCHA (Completely Automated Public Turing test to Computers and Humans Apart) and used as a verification tool which helps to protect sites from spam and misuse.
reCAPTCHA is a free and most commonly used CAPTCHA service managed by Google. It can easily solve by humans but hard for bots and other malicious software.
reCAPTCHA not only protects from spam but also benefits from human effort to computerize text and images. It is making possible to preserve old books, improve maps, and solve hard AI problems.
History of ReCAPTCHA
Luis von Ahn, professor of Carnegie Mellon University with his colleagues, developed the ReCAPTCHA. Initially, it was designed to find if a user is a human or not. However, soon it is started to use as a digitalizing source of books.
On September 16th, 2009, reCAPTCHA was sold to Google and used as the main feature of Google Books project where rare, ancient and out-of-print books are archived.
According to the Google,
With the use of reCAPTCHA, humans have digitalized over 13 million archived articles of The New York Times from the past 20 years or so in just a few months. Through mass collaboration, books that are impossible to be scanned by computers are digitalized as well as translated into different languages.
How does it Work
reCAPTCHA is not an open source software. It adopts an advanced risk analysis engine and adaptive CAPTCHAs to keep bots away from your site.
In 2012, it used pictures of house numbers taken from Google’s Street View to computerize it. In 2013, it implemented behavioral analysis to make more difficult CAPTCHAs. However, by 2014, the system changed where users are asked to choose a few images from a set of images.
In 2017, reCAPTCHA improved its mechanism to need no user interaction called ‘invisible reCAPTCHA’. It is the most recent development in CAPTCHA world and has made it difficult for bots and less friction to a human user.
It analyzes users browsing behavior to identify a user as compared to its predecessor which recognize a user through their clicking style.
These days, security of a website becomes very important, so having a CAPTCHA is a must to secure your site. We recommend using reCAPTCHA to stop bots because WordPress plugins are readily available to integrate it.