Why have a security code?

Well, believe it or not, in the ever-escalating world of SPAM, spammers search out forms like this one, and fill it with links to their Viagra site or whatever. 

This is an automated process, and most 'bots used aren't smart enough to figure out the simple code entry.  You've probably seen fancier examples of this technique, where you enter text from a distorted image.  These techniques are referred to with the acronym, CAPTCHA.

So, we apologize for the small inconvenience on your part, but we do value your input.

That's probably more information than needed, but if you would like more, here is a link to the Wikipedia entry on CAPTCHA.