Captcha

Captcha

Completely automated public Turning test. An automated test with the purpose of tell humans and computers apart.

Various forms of captcha are often used on web site forms, to try to block access by web-bots and yet permit access by genuine human users. A common form of captcha is to display an image of a word or number and require the user to enter the digits or letters of that word. The idea is that a human should be able to read and recognise the image but an automated bot would find it very difficult if not impossible to do so.