Captchas and Why We Use Them

If you have recently tried to send a message to us using one of the comment forms scattered about our site you have discovered that to send the message you have had to type in two words from an image that presents them in a distorted fashion. They are produced by a program called a Captcha.

The term CAPTCHA (for Completely Automated Turing Test To Tell Computers and Humans Apart) was coined in 2000 by Luis von Ahn, Manuel Blum, Nicholas Hopper and John Langford of Carnegie Mellon University.

Basically, the Captcha presents words that are usually unreadable by a computer program which helps to ensure that a spammer isn't sending junk or malicious messages through our forms.

While some folks hate to deal with Captchas, we have found a way to allow you to do good every time you send us a message.

Our Captchas are provided by reCaptcha, a free anti-bot service that also helps digitize old books and newspapers. As noted on the reCaptcha web site, computers using OCR software can figure out many of the words in these old documents, but not nearly all of them. So reCaptcha presents two scanned words to you, one that it knows is correct, and one that its OCR software couldn't figure out. If you get the one it knows right, then it assumes that you probably know what the other one is. Then it presents that same word to a bunch of other people, and if they say it is the same word that you said, then their computer has learned to recognize what that word is.

This is a good thing for those of us who rely on old books and newspapers to tell us more about our ancestors and the history of the places where we live since more and more of these documents are finding their way online.

So the next time you want to send us a message, remember you are helping expand our ability to read these old documents, and that is a good thing.