ReCaptcha, a play on the antispam tests known as Captchas (Completely Automated Public Turing Test To Tell Computers and Humans Apart), a test that people can pass, but machines cannot. People typically fill out Captchas so Web sites can verify that a human, rather than a spam bot, is behind the request for a new e-mail address, log-in, or membership. But with ReCaptchas, which are double-word tests, humans are also helping machines better recognize faded-ink or blurry words that have been digitally scanned from old newspapers or books–text that’s difficult for a computer to recognize optically. That way, people will eventually be able to sift through print archives with a more intelligent search engine.