Possible Duplicates:
Blocking comment spam without using captcha
Alternative to Annoying Captcha in Forms: How to SMELL the difference between a Human Customer and a Spammy Robot?
I need a simple and efficient way of detecting spam robots. (possibly in PHP/JS) I don't want them to insert tons of spam into my database, through a form.
Are there some good ways of doing this (not by using recaptcha)?