By Faithe Wempen

Each operating system (OS) is optimized for the hardware it runs on and the tasks the user is likely to want to perform. For example, the OS on a tablet computer is compact because there’s not much storage space for it, and it’s easy to use because most tablet users aren’t computer professionals.

On the other hand, the operating system for a server is designed to give a computer professional many options for managing and configuring a network and its devices, and neither compactness nor ease-of-use are major factors in that.

Some operating systems are designed to run on just one specific platform. A platform is a type of hardware. For example, most Windows-based computers run on the Intel platform, sometimes called the IBM-compatible platform.

Several other operating systems can also run on that platform, including Linux and recent versions of Mac OS X. On the other hand, most tablets and smart phones support only one operating system — the one they come with.

An operating system can have either a graphical user interface (GUI) or a command-line interface. GUI interfaces are the norm in operating systems designed for personal computing devices like desktops, notebooks, tablets, and smart phones. Users interact with the graphics they see onscreen by using a keyboard, mouse, or touchscreen.

In a command line interface, you type each command manually; the area of the screen where your typing appears is the command prompt. You have to memorize the commands to use, or keep a reference book handy.

Why on earth would anyone want to type commands at a command prompt, if they had any other choice? Well, primarily because it’s easier to do certain things at a command line than it is to do them in a graphical environment.

Most such things are pretty technical and only IT professionals do them. That’s why a command line interface is found primarily in operating systems designed to be used on servers, such as UNIX and Linux. The figure compares a GUI OS with a command-line OS.