Network To[ology

There are many ways in which computer can be connected together in a computer network.The ways in which nodes are connected in a network is called network topology.Shortly the term network topology refers to the physical layout  or shape of the network.
1-Bus topology
2-star topology
3-Ring topology
4-tree topology
5-Mesh topology

Network Models

A network model represents the architecture of computer network.The most popular network models are described below.
1-Client-Server Model
2-peer-to-peer Model
1-Client- Server Model
A network architecture in which one or more computer act as servers and other computer acts client computer is called Client server model
2-Peer-to-peer Model
A network architecture in which all computer on the network have equal status and no ons has control over others is called peer-to-peer model

Brief history of the Internet

The work to develop a communication system was in 1960 during the cold war between the USA and Russia.In 1957, Russia launched Sputnik, the first artificial earth satellite.in respons. to the launching of Sputnik the American established the advance to develop a communication system.
In 1969 ARPA established a small computer network.During 1970 s and 1980 several universities & research organization development their own computer network.Similarly many other network for military use were developed.

Internet

The words Internet stands for International Network.Internet is the largest computer network in the world. The information  can be sent and received through internet all over the world.Actually internet is the network of many computer networks around the world.It consists of millions of private, public, academic, business,and government networks.The communication protocol used for Internet is TCP/IP.
The Internet connects millions of computers.These computer are linked through different communication media.The commonly used communication media are telephone lines, fiber optic cables,microwave and satellite.
A large number of books, newspapers,magazines,encyclopedia,and other types of materials are available in electronic form on the internet.We can find information about almost any thing of the world.We can access latest information or news on any topic

Communication Media

A path through which data is transmitted from one place to anther is known as communication media.It is also known as communication channel.The twisted pair cable,fiber optic cable,microwave,satellite etc
Type of Communication Media
1.Guided Media
2.Unguided Media
1-Guided Media 
The types of communication media in which communication  devices are directly linked with each other is called communication media.
Example:-
Twisted pair wire
Coaxial cable
Fiber optic cable
2-Unguided Media
The types of communication media in which communicatuon devices sends and receives data singnal through air is called unguided media
Microwave
Communication Satellite
Mobile communication

Software

A set of instruction given to the computer to perform the particular task , is called software,Software is also called computer program.
Software tells the computer what to do and how to do.A computer performs different operation according to the instruction of software.Software is development in computer programming language.
Types of Software
1.System Software
2.Application Software

1-System Software
A program or set of program that is especially designed to control different operations of components system is called system  software

2-Application Software
A program or set of program that are especially designed to solve the specific problems of users are called application software.
Categories of Application Software
1.Custom-Built software
2.Packaged software

Computer Hardware

The physical components of a computer are called hardware.You can touch ,see and feel hardware.The input/output devices such as keyboard,mouse,printer,monitor,keyboard,printer,LCD and etc,CPU ,memory unit etc,are examples of hardware.
Hardware Devices
Primary Hardware components
1.Input devices
2.Processor
3.Memory unit
4.Output devices
5.Secondary storage devices
Hardware Devices
Input Devices                            Keyboard,Mouse,Microphone etc.
Output Devices                         Monitor,Printer,Speaker etc.
Main Memory                           Ram and Rom
Secondary Memory                   Hard disk,USB Driver,Floppy Disk and etc.
Inter-connectors                        Cable,Ports,Buses etc.
Network Devices                      Modem,Bridge,Router etc.