First thing that amazes a new user connected to a network is the possibility of connecting (through Telnet or other programs) to another computer, and then work, just as if it was there. He can launch programs on the server and use the presumed bigger computing power of the server, he can use all his files the way he likes others. And those computers can be thousand miles away...

Also, through the remote management, you can configure a server across the Internet, with just the help of a Web Browser. Linux also comes with an excellent software for managing emails (Sendmail) which is, you know now, free and widely used. But there are more : Qmail or Exim are a good choice, because they are less difficult to configure, but as a compromise they have less options too. As a network operating system , Linux has all the functionality of a commercial OS and even more.

It supports: multiple users, password security, file permissions, disk quotas (to limit a user's disk usage), transparent use of many storage devices, even interconnected in a network by "mounting" them in the same root directory, very flexible network configuration, servers for telnet, SMB file system, finger, ftp, web, firewalling, packet control, lots of other advanced networking features (Linux can be excellent as a router for example).

As an operating system, Linux has the following features: great multitasking and process management, very good speed, flexible storage devices configurations, very flexible kernel configuration (because the kernel sources are freely available, everyone can compile its own kernel based only on useful drivers for a specific computer, or a full kernel with support for many things), kernel modules inserted on-the-fly depending on the needs, very good stability and protection from the kernel, good support for the most known hardware pieces (even if there is no support for some others).

With the new drivers and libraries available for Linux, it is enlarging its area even in the desktop system, as a multimedia system (although there will be some time until Linux will raise the multimedia stack). And how about having programs (in text or graphical mode) running on a remote server, with the output on your own screen? Lots of these and others I did not mention here, show a very good or excellent functionality of this operating system.