Why would a URL contain a GUID or Session ID in it?

[jm]

What would cause a URL to have a GUID in it? I have a guy who made a
web page and when you go to default.aspx it works, but rewrites the
URL to have a something like http://myserver/path/(some long guid/hex
number with parathesis)/default.aspx. That number changes every
time. Is it a session id? Thanks.

 

[sloan]

CookieLess set to true?

 

[Mark Fitzpatrick]

It could be if the site is using a cookieless session, in other words
putting the session id in the url instead of a cookie, which is good if you
decide you can't rely on cookies being enabled on the browser.