Google reCAPTCHA is a commonly used spam prevention tool and mechanism. Thousands of websites and blogs fights spam using reCAPTCHA plugins available in PHP, ASP.NET and Ruby. reCAPTCHA helps prevent automated abuse os your website. Automated abuses like comment spam or bogus registrations are very commom. reCAPTCHA helps prevent this by generating tests that only humans can pass but computer programs cannot (at least the current computer programs).
CAPTCHA (Completely Automated Public Turing Test To Tell Computers and Humans Apart) is a proven tool that replaces methods that randomly generats useless characters which users grow tired of continuosly typing in. Spammers employed smart OCR programs that can read such randomly generated images with text. reCAPTCHA succeeds here by implementing methods that generates certain distorted words that cannot be read by the Optical Character Recognition tools and constructs a CAPTCHA image using those words.
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reCAPTCHA originally developed at Carnegie Mellon University and in 2009 Google acquired reCAPTCHA . Even though it is very popular as a spam prevention mechanism used by websites , the reCAPTCHA is mainly used for digitizing the archives of The New York Times and books from Google Books.
Get reCAPTCHA for your websites
reCAPTCHA is a free service. To make the life easy for website owners reCAPTCHA offers plugins for several web-application platforms, like ASP.NET, Ruby, or PHP. There are plugins available for WordPress and Mediawiki platforms. These plugins offers the following services,
Prevents Comment Spam in Blogs and Websites
- The user will be presented a CAPTCHA and user needs to type in the words. If the user has trouble reading the CAPTCHA challenge, he or she has the option of requesting a new one by refreshing the CAPTCHA. If this also does not help, there the user can use the audio challenge.
Helps to prevents spam during Website Registration
- Use CAPTCHAs to ensure that only humans can complete the registration process and obtain accounts.
Mailhide
- The project Mailhide from reCAPTCHA protects email addresses on web pages from being harvested by spammers
How reCAPTCHA works?
Once you implement the reCAPTCHA in your website , then the the reCAPTCHA tests are retrieved from the central site of the reCAPTCHA project through a JavaScript API It supplies the words to be deciphered. Also the server makes a callback to reCAPTCHA after the request has been submitted.
Get reCAPTCHA for WordPress
WP-reCAPTCHA WordPress plugin integrates reCAPTCHA anti-spam methods with WordPress including comment, registration, and email spam protection.
- Download and Unzip the WP-reCAPTCHA plugin to recaptcha folder into your WordPress wp-content/plugins directory.
- Activate the plugin and you need to enter a public and private API key (You can sign-up for the keys at the reCAPTCHA site using the link provided in the plugin page itself).
- After activation reCAPTCHA widget should appear on the comments page.
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It's a free captcha service and has copy & paste installation