Actually, that's part of a standard cookie
Domain and path
Each cookie also has a domain and a
path. The domain tells the browser to
which domain the cookie should be
sent. If you don't specify it, it
becomes the domain of the page that
sets the cookie, in the case of this
page www.quirksmode.org
. Please note
that the purpose of the domain is to
allow cookies to cross sub-domains. My
cookie will not be read by
search.quirksmode.org
because its
domain is www.quirksmode.org
. When I
set the domain to quirksmode.org
, the
search sub-domain may also read the
cookie. I cannot set the cookie domain
to a domain I'm not in, I cannot make
the domain www.microsoft.com
. Only
quirksmode.org
is allowed, in this
case.
The path gives you the chance to
specify a directory where the cookie
is active. So if you want the cookie
to be only sent to pages in the
directory cgi-bin
, set the path to
/cgi-bin
. Usually the path is set to
/
, which means the cookie is valid
throughout the entire domain. This
script does so, so the cookies you can
set on this page will be sent to any
page in the www.quirksmode.org
domain
(though only this page has a script
that searches for the cookies and does
something with them).
Source
You may want to read more about cookies.