Windows 7 and Domains

With more and more people working from home on laptops or having the option to do so these days, Microsoft’s developers decided to include in Windows 7 the capability for these mobile workers to enjoy some of the media content they have on the other PCs in their Home Group while they work. At work, instead of a Home Group, the laptops are usually joined in domains, which are groups of computers and other devices to which certain permissions are attached.
Those work computers used a specialized domain controller system to manage the permissions. Any computer in the domain would log in to the domain controller, rather than directly into the local system.
Windows Home Group brings that centralized permission capability to your home computer. When you create a Home Group, you are in essence creating a small, localized domain. One nice feature about this is that joining the Home Group doesn’t obstruct you from logging in to your work-based domain at the same time. Normally, your computer is only allowed to belong to one domain at a time. Home Groups allow your computer to belong to a work domain and your Home Group simultaneously.
This enables the domain-joined computer to consume the media available on Windows 7 PCs in the home, watch TV through WMC, listen to music via WMP, or print to the printer on another Home Group PC. It’s done simply by entering the same password you use to connect to your Home Group.
The only apparent difference is that protected content on the corporate network is never shared with the Home Group computers other than the one that’s connected. In essence, the domain-joined computer can see and use the resources on both networks, but nothing else can. Thus, other computers on your work network can’t see the resources available through your Home Group, and other computers on your Home Group can’t see the systems on your company network.