If you've ever signed up for an e-mail account or bought something online, you've probably seen them: puzzling strings of letters and numbers that you're forced to type in.
They're called Captchas (an acronym for "Completely Automated Turing Test To Tell Computers and Humans Apart") and they're a major line of defense against spam. Without them, spammers' computers could automatically sign up for millions of e-mail accounts. But computers can't read letters and numbers that are slightly distorted. The captchas require a human to type them in, and that shuts down the spammers.
But while Captchas are a helpful tool, they can also waste time. In fact, hundreds of thousands of hours are wasted every day by people solving captchas around the world. But now there's a professor who wants to turn that wasted time into an effort to preserve the world's great literature, reports CBS News technology correspondent Daniel Sieberg.
Seven years ago Carnegie Mellon computer science professor Luis von Ahn helped create captchas for Internet giants like Yahoo. Captchas have been successful in slowing spammers, and now he wants to improve on his idea for a project he believes is essential to the world's history: preserving books.
"There are hundreds of millions of books that need to be digitized," he said, "and that's what re-captcha is going to allow you to do."
With re-Captcha, von Ahn is asking all Web sites to switch to his new tool. No catch. So instead of typing in captchas that are gibberish stuff like "vr4tyw77," you would type in actual words -- words from books that need to be digitized. Those books then become part of the World Wide Web, accessible to all of us.
Brewster Kale runs the Internet Archive Project and is already seeing dividends from Luis' efforts.
"With 500 million people typing in words everyday, we can get something done in a couple of years that would have taken hundreds," he said.
All thanks to the power of the Internet and a brilliant professor -- with a little help from millions of his closest friends.