Operating System:An operating system is a software or collection of various programs for a computer system that is responsible for the managing of various activities of the computer and provide a way for sharing of computer resources.Operating System provide interface between hardware and user without operating system a computer is useless.
Users interact with operating systems through Command Line Interfaces that support only command not any graphical interaction or
Graphical User Interfaces known as GUIs. In short, operating system enables user interaction( that support graphical interaction with user) with computer systems.

Components of the operating system:
The operating system combined a set of software packages that can be used to manage interactions with the hardware.In this we use the following components.
The kernel:- which perform the basic functions such as management of memory,
processes, files, main inputs/outputs and communication.
The shell:- Shell support communication with the operating system through language or we can say as command with a language,
For example user control the peripherals without knowing the characteristics of the hardware used, management of physical addresses, etc.
The file system:- File system allowing files to be recorded in a tree structure or data storage purpose.

Types of operating system:

Real-time Operating System:->Real-time operating systems often use special scheduling algorithms they perform task depend on time.
Multi-user and Single-user Operating System:->Time-sharing system can be classified as multi-user systems
as they enable a multiple user access to a computer through the sharing of time
Multi-tasking and Single-tasking Operating Systems:->Allows more than one program to run concurrently.
Distributed Operating System:->this type of os manages a group of independent computers and makes them
to be a single computer is known as a distributed operating system
Embedded System:->They are designed to operate on small machines like PDAs or chip based system..

Last edited by satyedra pal; 16Apr2010 at 11:27.. Reason: some headings was not seeing clear.