internet access through firewall

I have been meaning to ask this question for some time.

Win XP Pro --- What possible reason can windows explorer have to always be trying to access the internet?

If you type a web address or network address into Explorer, it'll usually open Internet Explorer but a lot of firewalls will catch Explorer accessing the network/Internet at that point. If I recall correctly that is. Other than that, I can only see using it to browse network devices. But I'm sure there's other reasons too that other members might be able to shed some light on.