Peripherals and system parts are a collection of electronics that work together in order to perform a specific task. The program that every computer uses to control and manage all these parts is called the operating system (OS).
For example, a user that wants to write a document and print it out on a network printer needs an application like Microsoft Word to accomplish this job. Microsoft Word works with the OS in order to accomplish all the word processing tasks. The operating system controls all the input and output functions. All the personal computers, the servers and the handheld devices require an OS in order to function.
The operating system works like an interpreter between software applications and the hardware. An individual interacts with the computer hardware through an application, like Microsoft Excel, Adobe Photoshop, etc. Software applications are made for a particular purpose. On the other hand the OS is responsible for the communication between the software application and the computer's hardware.
When a PC is powered on it loads the operating system from the hard disk into RAM. The part of the operating system that interacts directly with the hardware is called kernel. The part of the operating system that it is visible to the user is called shell. The user can use the shell from the command line interface (CLI) or from the graphical user interface (GUI).
The user that uses the CLI interacts directly with the OS in a text-based environment by typing commands at a command prompt. The computer executes the command and provides textual output. The user can also use the GUI and control the computer from an environment that uses graphical images, multimedia, as well as text. This is more user-friendly and requires less knowledge than CLI. Therefore, most users work with GUI environments. Microsoft Windows and Linux operating systems offer both GUI and CLI.
All the modern operating systems allow the user to multitask. The OS keeps track of which resources are used by which software program.
In order to work with devices that are not directly attached to the PC, a special software application must be installed that allows a device to send and receive data from the net. This is called redirector and usually it is an integral part of the OS but sometimes you need to install it separately as a network client. After you install it, the OS becomes a network OS (NOS).
A network operating system includes complex scheduling and user management software that allows a hardware device to share network resources between several users and treat network devices like all the directly attached devices.
