Secrets behind the free program reCAPTCHA: Turn Internet users into 'free workers' to electronically 17,600 books a year

Internet users are too familiar with CAPTCHA, a frustrating step when surfing the web to prove users are real people, not robots.

The term CAPTCHA is an acronym for Automatic Computer and Human Distinction System (Completely Automated Public Turing test to Tell Computers and Humans Apart) created by Luis von Ahn, at Carnegie Mellon University in 2007.

CAPTCHA is quite effective in preventing mass-denial-of-service attacks or stealing data, and especially this program is completely free, so many websites use it.

Founder Lui realized that, in order to complete a CAPTCHA template each person only takes a few seconds, if counting a huge number of users on the Internet, there are hundreds of hours of 'wasted' hours pouring into CAPTCHA each day. Therefore, Luis launched reCAPTCHA to take advantage of these valuable working hours.

Basically, reCAPTCHA is still a normal and completely free, easy to use CAPTCHA program. Very quickly, reCAPTCHA has been used by website owners as their default defense.

But few know that behind this free program is a "genius" business model, turning tens of millions of Internet users into "typewriters" that they don't know.

How does reCAPTCHA work?

reCAPTCHA requires users to enter 2 different letters instead of 1 word like other recognition software. In addition, the words on reCAPTCHA are also very easy to see because they are taken from physical documents (books, newspapers, leaflets .) that OCR - Optical Character Recognition, text recognition software cannot handle.

OCR software is used to transfer data (articles, book pages .) from print to electronic version for storage and distribution. But the disadvantage of OCR is that it is impossible to recognize the word, even if it is clear if the page shows signs of fraying, old or degraded.

With reCAPTCHA, in the two words the user must enter a recognized word and store it in the data warehouse, the other word is taken from the list of words that OCR cannot read above.

When an OCR image is unrecognizable, at least 6 users use one word instead, reCAPTCHA will recognize it as a successful "electronic" word.

How is reCAPTCHA worth?

With such accurate readability, reCAPTCHA has been hired by the prestigious New York Times newspaper to digitize all old posts. And only a few months later, all the New York Times articles within 20 years before the computer appeared were reCAPTCHA electronicized easily.

After 1 year of operation, reCAPTCHA has successfully electronicized more than 440 million words, equivalent to nearly 17,600 books!

In 2009, Google spent a large amount of money (at least $ 30 million in anticipation) acquiring reCAPTCHA to use for Google Books, making it the world's largest electronic library after only a few years.

In addition, reCAPTCHA is also used by Google for many other purposes such as solving house codes, street names on Google Maps Street View or distinguishing the vehicles .

Google quickly proved that buying reCAPTCHA is absolutely right. Only a short time, Google has reclaimed the purchase of reCAPTCHA through the above applications.

See more:

1. The origin of CAPTCHA and reCAPTCHA
2. Apple CEO said that learning code is more important than learning English
3. How must Samsung's smartphones and smartwatch go through a rigorous quality control process?