Prevent robots from submitting data

Spam is/was/has been the biggest problem in the internet. Even in your application. You are developing and testing your web application, it works perfect. but when you deploy it on the internet, huge amount of data is submitted by someone, which is very big problem for you. So you have to prevent from spam like data submission. People have tried many methods to protect from spams, by the time the only method is proven and accepted as standard. Challenge/response CAPTCHA method. According to Wikipedia, CAPTCHA ("Completely Automated Public Turing test to tell Computers and Humans Apart") is a challenge response test which is used to check if the user is human or not. CAPTCHA is used exclusively in applications where user input is required. These applications include blogs, forums, and portals. From the following resources, you can find CAPTCHA implementations and tutorials in your preferred platform.

ASP.NET

• http://www.15seconds.com/issue/040202.htm
• http://www.codeproject.com/aspnet/CaptchaControl.asp
• http://www.codeproject.com/aspnet/CaptchaImage.asp
• http://www.codeproject.com/aspnet/CaptchaNET_2.asp
• http://www.codeproject.com/aspnet/CaptchaLIKE.asp

Java

• http://simplecaptcha.sourceforge.net/
• http://jcaptcha.sourceforge.net/
• http://www.ansir.ca/newsletters/volume5.jsp

PHP

• http://www.white-hat-web-design.co.uk/articles/php-captcha.php
• http://www.puremango.co.uk/cm_php_captcha_script_113.php
• http://www.phpclasses.org/browse/package/2487.html
• http://www.codewalkers.com/c/a/Miscellaneous/Creating-a-CAPTCHA-with-PHP/
• http://milki.erphesfurt.de/captcha/
• http://www.webcheatsheet.com/php/create_captcha_protection.php

Rails

• http://www.busyashell.com/blog/articles/2006/07/06/rails-captcha-validation-with-javascript
• http://www.rubyonrailsblog.com/articles/2006/09/29/use-the-ruby-captcha-gem-for-rails-user-registration
• http://captchator.com/
• http://ajaxonrails.wordpress.com/2006/10/24/captcha-in-ruby-on-rails-customize-the-use-of-captcha-in-the-plugin-validates_captcha/