When you sign up something like a free e-mail account, you may be presented with a CAPTCHA. the most common form of CAPTCHA is an image of several distorted letters. CAPTCHA stands for:
- "Coverage Analysis and Planning Tool for Computers and Humans Apart."
- "Completely Automated Public Turing test to tell Computers and Humans Apart"
- "Completely Applied Parallel Technologies for Communication and Hardware Apart".
- "Comparable Additional Protected Turing test to cell Computers and Humans Apart".
