Most of you have experienced with CAPTCHA test, let’s see the detail information about it.
What is CAPTCHA?
CAPTCHA (Completely Automated Public Turing Test to Tell Computers and Humans Apart) is known as a type of Human Interaction Proof (HIP).It is a type of challenge-response test used in computing to determine whether the user is human being or computer program.
You’ve probably seen CAPTCHA test on lot of Web sites. The most common form of CAPTCHA is an image of several distorted letters & numbers.
It’s your job to type the correct series of letters into a form. If
your letters match the ones in the distorted image, then you will pass
the test.
For example, a free e-mail service
might find itself attacked by account requests from an automated
program. That automated program could be part of a larger attempt to
send out spam mail to millions of people. The CAPTCHA test helps to identify which users are real human being and which ones are computer program.
Applications:
- Registration forms on Web sites often use CAPTCHAs. For example, free Web-based e-mail services like Hotmail, Yahoo! Mail or Gmail allow people to create an e-mail account free of charge.
- It is used to prevent people from using bots (Automated program) to assist with massive downloading of content from multimedia websites.
- It is used in online message boards and blog comments to prevent bots from posting spam links as a comment or message.
- CAPTCHAs are used to prevent bots from using various types of computing services, collecting certain types of sensitive information and preventing bots from taking part in online polls
How to use:
reCAPTCHA is a free CAPTCHA service. If you run a website that
suffers from problems with spam, you can put reCAPTCHA on your site.
For some applications (such as WordPress and Mediawiki), we have plugins
that allow you to use reCAPTCHA without writing any code. We also have
easy-to-use code for common web programming languages such as PHP.
References:
http://www.captcha.net/
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