A CAPTCHA is a program that can generate and grade tests that humans can pass but current computer programs cannot. For example, humans can read distorted texts as the one show below, but current computer programs can't:
The term CAPTCHA (for Completely Automated Public 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. At the time, they developed the first CAPTCHA to be used by Yahoo.
What CAPTCHA could do for you?
- Preventing Comment Spam In Blogs
- Protecting Website Registration
- Online Polls
- Preventing Dictionary Attacks
- Search Engine Bots
- Worms and Spam
Where Can I Get a CAPTCHA For My Site?
* This article is copyrighted from Google.