Have you ever seen one of those garbled text blocks on a registration form? Sometimes they can be pretty frustrating when all you want to do is sign up for an online service or request more information. This increasingly common test is called a CAPTCHA, an acronym for Completely Automated Public Turing test to tell Computers and Humans Apart.

The whole point of using a CAPTCHA is to prevent a non-human from submitting the form. If you’ve ever run a web site with a form on it, you’ve likely received lots of spam as a result. The CAPTCHA can help quite a bit in this regard.

One important fact to keep in mind, however, is that not all CAPTCHAs are created equally. Some, even those difficult for humans to read, can be quite easy for a bot to crack. Some popular open source programs include a built-in CAPTCHA mechanism, but also provide plugins for using a different CAPTCHA. It is very beneficial to research the options and their efficacy against spam.

As an example, consider phpBB, a very popular open source forum system. Out of the box, it has a few CAPTCHAs you can pick from. However, they acknowledge that one of the defaults is extremely weak and is not recommended. With a little bit of extra configuration, you can enable a more robust CAPTCHA that will keep the spam at bay.

If this all sounds a bit too technical or if you’re experiencing high levels of spam on your forms and don’t know what to do, please send us a note. We would be happy to take a look at your site and help you implement a proper CAPTCHA.