Desktop sharing is a common name for technologies and products that allow remote access and remote collaboration on a person's computer desktop through a graphical Terminal emulator.
The most common two scenarios for desktop sharing are:
Remote log-in allows users to connect to their own desktop while being physically away from their computer. Systems that support the X Window System, typically Unix-based ones, have this ability "built in". Windows versions starting from Windows 2000 have a built-in solution for remote access as well in the form of Remote Desktop Protocol and prior to that in the form of Microsoft’s NetMeeting.
The open source product VNC provides cross-platform solution for remote log-in. Virtual Network Computing (VNC): Making Remote Desktop Sharing Possible Remote desktop sharing is accomplished through a common client/server model. The client, or VNC viewer, is installed on a local computer and then connects to the network via a server component, which is installed on a remote computer. In a typical VNC session, all keystrokes and mouse clicks are registered as if the client were actually performing tasks on the end-user machine.
The shortcoming of the above solutions are their inability to work outside of a single NAT environment. A number of commercial products overcome this restriction by tunneling the traffic through rendezvous servers.
Apple users require Apple Remote Desktop (ARD)
Real-time collaboration is much a bigger area of desktop sharing use, and it has gained recent momentum as an important component of rich multimedia communications. Desktop sharing, when used in conjunction with other components of multimedia communications such as audio and video, creates the notion of virtual space where people can meet, socialize and work together. On the larger scale, this area is also referred as web conferencing.