[Zope] Zope and garbage collection

[Ted holden]

Dumb question here:

Having a user browse to a web page which involves a python 
object clearly creates the object.  What happens when the user either 
switches his browser to some other web site or turns off his modem?  Does 
that somehow delete the object and, if not, does the developer need to 
concern himself with garbage collection?  In other words, is garbage 
collection automatic with Zope?