If you have your own site and have contact form on it you probably get a lot of spam messages from that web form, what to do to fight it? install CAPTCHA(Completely Automated Public Turing test to tell Computers and Humans Apart) in your form. What is captcha? according to wikipedia it is "A distorted image of letters and numbers used to prevent automated use of websites. Anything that a human must do to prove that they are not a computer." So, how to install this thing? There are plenty of php classes and functions on the web helping you to do exactly it. Just search for captcha and you will find one. I use captcha tool from http://puremango.co.uk and it works nicely, the generated words are human mind relative, so, easy read by human being and very complecated for robot. It works the same way as all captchas do - when the form is loaded, the captcha is generated and the content of it is saved in $_SESSION variable and on submition of the form the content of session variable is compated to inserted text and form is processed according to this comparison result. Very smart and easy. Try to install captcha on your site form and you will see effectiveness of it.