In Windows XP, you can actually get at shared folders and printers in two ways: through traditional LAN methods or via the World Wide Web. This last method shouldn't come as much of a surprise these days; I think even washing machines come with a Web interface now.
The traditional methods are based on the Microsoft Networking protocol (called NetBT, or NetBIOS over TCP/IP, also called SMB, or Server Message Block), which has been around for a very long time.