[Javascript] automatic filling of login field

[Bernu Bernard]

Hi,
On some site, when there is a login field in a form like
<form ...>
	<input type="text" name="login">
	...
</form>
the field is automatically filled the second time you come back to  
that site.

In the html I write this never happens.
What should I add (or remove) to have this automatic filling working.

Is this pure HTML feature or is it some javascript/cookie to do ?

Thanks,

Bernard