CAPTCHA stands for Completely Automated Public Turing test to tell Computers and Humans Apart. It is a kind of challenge-response test that is used in computing to distinguish between humans and machines. The basic CAPTCHA requires that you key in the letters of a fuzzy image, sometimes with the supplement of a masked series of letters or digits that emerge on the screen.

CAPTCHA can create and score tests automatically. They admit all humans and discard almost all machines. Humans can usually read tarnished images, but OCR machines cannot. [You can find out more details in http://www.protectwebform.com/]

While business websites wish to attract maximum traffic they are wary of spammers misusing your personal information. Therefore, they provide a feature on their site to get response from visitors and avoid spam. Since posting an email on your website is a sure shot invitation for spammers, they use a whole lot of tricks and methods to conceal your email address so that spammers can't find it.

The most common method to do this is by embedding Java script in the web page to capture the email address when the page is displayed to the visitor. An enhanced alternative is to use CAPTCHA along with the website forms. This is used extensively by big websites which require you to sign up.

The person registering with these sites is required to identify and enter some indistinct characters shown on the screen for confirmation before submitting the form. The logic here is that computer generated programs will not be able to identify these unclear characters and alphabets. The form is therefore construed as automatically authenticated and submitted by a human visitor rather than some computer generated program.

A CAPTCHA is intended to avert bots ? programs that model as humans on the Internet ? from misusing Internet services. Bots are created not to rule but to sell, sign up for numerous free email accounts every moment, sending millions of Spam messages from them. They penetrate chat rooms, accumulate personal information and posts links to promotional sites. They create worms, break password systems, assault confidentiality, and deplete resources. With CAPTCHA Plugin, you can customize your CAPTCHA with preferred colors and fonts. You can also decide among loads of image types. [See http://www.protectwebform.com/plugin_wordpress].

Smart CAPTCHA is a technique of improving the CAPTCHA to make work easier. It was proposed by ProtectWebForm. They recommend that you join the CAPTCHA with JavaScript support. They planned to use an easy script, which fills up the CAPTCHA fields and conceals the image and the field from human eyes because most spam robots find it difficult to carry out scripts. They have used the method of safety through shadows. They defend your site because authors do not come across the exact kind of JavaScript in question. For furher details visit http://www.protectwebform.com/smartcaptcha.

Once you have inserted the CAPTCHA code in your web pages you can be sure that the registration is being tendered by a human being and not by some computer generated process. No wonder, the use of CAPTCHA is becoming increasingly popular.