I'm working on a PHP script and I noticed that with the action attribute set to index.php yields the same results as leaving the attrib blank (""), so... why is it required?

It is requires by the w3c specification.

Now, if you don't have it, the browser adds it with a default to the current URL, but it's a browser specific value.

You could have a browser who don't set it at all.

Originally Posted by tripy

It is requires by the w3c specification.

Now, if you don't have it, the browser adds it with a default to the current URL, but it's a browser specific value.

You could have a browser who don't set it at all.

Alright, but can I use '/' instead? so action="/" is the main page.

What you can get away with is not the same as what you ought to do. What's so big a deal about putting in the form action?

Alright, but can I use '/' instead? so action="/" is the main page.

Sure you can...
But as asked said Jeremy, why is it such a big deal ?

Usually the script that displays some form processes that form also. In this case I always set form action="". If I display some form on every page of the site, e.g. search form, then it is reasonable to set certain form action, e.g. action="/search/".