How can I block spam in my forms?

Most spammers are attempting to post links to urls they want you to click on, or get posted to a website. 

By taking advantage of this trait, you can block spammers by checking for any url's in the incoming form fields, like so:

foreach($_REQUEST as $var => $val) {

  if(strpos($val,"http://") !== false) {

     // print out an error here, or return to form

  }

}

If you need to allow a url in a specific field, you can exclude that field from checking in the loop above.