Okay, here’s the problem— bots. Bots are little programs created to crawl all over the Internet looking for ways to cause trouble. Often they’re made to help spammers do their dirty work. Bots will create accounts and pretend that they are real people. They might signup for online email accounts or leave comments on a blog.
Because of bots, websites need a way to verify that only humans are signing up for their services. They need to ask a question that humans can answer but computers cannot. Enter the CAPTCHA. CAPTCHAs are those squiggly letters you’re asked to enter when you signup for things online. Here is an example:
A recent estimate suggests that 60 million CAPTCHAs are solved by humans each day— that’s a lot of reading and typing! The folks at reCAPTCHA have decided to put all that human power to work. Using their service, you enter words taken from books that have been scanned in but couldn’t be converted by a computer. The system turns both words into CAPTCHAs for you to solve. It knows the answer for one of the words but not the other. Since humans can read better than computers, you’re actually helping to digitize books and preventing spam.
You can help the book digitizing effort by adding reCAPTCHA to your site. You can use it to protect your email or your blog’s comments section; reCAPTCHA makes implementation easy.
Hear more about reCAPTCHA on a podcast from the Museum of Science in Boston.
Hear an in-depth discussion about CAPTCHAs on Security Now—a podcast by security expert Steve Gibson. (Episode 101- the discussion starts at 33:47)