VNC stands for Virtual Network Computing

Network administrators should be familiar with VNC which is the poor man’s
PCAnywhere. VNC stands for Virtual Network Computing and was developed by
AT&T Laboratories Cambridge. VNC is easily to install and use and is the
remote console utility of choice for penetration testers and hackers. It can be
run as an application or as a service. It is also widely used as a legitimate
support tool to make remote administration of win32-based servers. Check it out
for its own value and to be familiar with its characteristics.

The important factors which distinguish VNC:

No state is stored at the viewer.
This means you can leave your desk, go
to another machine, whether next door or several hundred miles away, reconnect
to your desktop from there and finish the sentence you were typing. Even the
cursor will be in the same place. With a PC X server, if your PC crashes or is
restarted, all the remote applications will die. With VNC they go on running.
It is small and simple.
The Win32 viewer is about 150K in size and can
be run directly from a floppy. There is no installation needed.
It is truly platform-independent.
A desktop running on a Linux machine
may be displayed on a PC. Or a Solaris machine. Or any number of other
architectures. The simplicity of the protocol makes it easy to port to new
platforms. There is a Java viewer, which will run in any Java-capable browser.
There is a Windows NT server, allowing you to view the desktop of a remote NT
machine on any of these platforms using exactly the same viewer. Note that the
NT server is not multi-user.
It is sharable.
One desktop can be displayed and used by several viewers
at once, allowing CSCW-style applications.
It is free!
You can download it, use it, and redistribute it under the
terms of the GNU Public License. Both binaries and source code are available
from the download page, along with a complete copy of documentation.