basic concepts

Introduction
This is a continuation of my series of articles on the terms and concepts that are frequently asked in IT interviews. This article is an attempt to discuss the salient terminologies and concepts related to Computer networking that are often asked in interviews. Although an article on Computer Networking concepts and terms would run for many pages, I have discussed only important ones to make it fit in one article.
Computer Network
A Computer Network implies two or more computers those are linked together through some software, hardware, etc for the purpose of exchanging data and information.
Internet
The Internet is a network of networks. It is "the worldwide, publicly accessible network of interconnected computer networks that transmit data by packet switching using the standard Internet Protocol (IP)."
World Wide Web
The World Wide Web or WWW is a hypertext based distributed information system. It "is the global network of hypertext (HTTP) servers that allow text, graphics, audio and video files to be mixed together." It is an "information space in which the items of interest, referred to as resources, are identified by global identifiers called Uniform Resource Identifiers (URI)." According to Tim Berners-Lee, inventor of the World Wide Web, "The World Wide Web is the universe of network-accessible information, an embodiment of human knowledge."
Modem
A modem is a modulator-demodulator device that is used for converting the transmission signals from digital to analog for transmission over voice-grade phone lines. While the digital signals are converted to a form suitable for transmission over analog communication at the source, the reverse happens at the destination where these analog signals are returned to their original digital form.
Network Interface Controller
A network card, network adapter or the Network Interface Controller (NIC) is a piece of computer hardware that facilitates the systems in a network to communicate.
Broadcasting
When the information transfer is from one system to many systems using the same means of transfer then such a network is known as a Broadcasting or Multicasting.
Unicasting
When the information transfer is from one system to any other single system using the same means of transfer then such a network is known as Point-to-Point or Unicasting.
Bandwidth
Network bandwidth or network throughput is a measure of the data transfer rate or the amount of data that can pass through a network interface over a specific period of time. This is expressed in bits per second or bps.


Broadband
This is a wide-band technology that is capable of supporting voice, video and data. It is "a transmission medium capable of supporting a wide range of frequencies, typically from audio up to video frequencies. It can carry multiple signals by dividing the total capacity of the medium into multiple, independent bandwidth channels, where each channel operates only on a specific range of frequencies."
Integrated Services Digital Network (ISDN)
Integrated Services Digital Network, an international standard for end-to-end digital transmission of voice, data, and signaling facilitates very high-speed data transfer over existing phone lines.
Network Load Balancing
Network Load Balancing may be defined as a technique that "distributes the network traffic along parallel paths to maximize the available network bandwidth while providing redundancy."
Local Area Network
LAN also known as Local Area Network are networks restricted on the bases of the area they cover. These networks stretch around an area of 10 meters to 1 km. "LANs enabled multiple users in a relatively small geographical area to exchange files and messages, as well as access shared resources such as file servers and printers." The commonly used LAN devices include repeaters, hubs, LAN extenders, bridges, LAN switches, and routers.
Metropolitan Area Network
MAN also known, as Metropolitan Area Network is a network that is larger than LANs spreading across an area of 1 km to 10kms. A simple example for this type of network is the branches of a bank spread across the city and are connected for information exchange.
Wide Area Network
WAN also known, as Wide Area Network is a network that is larger than a MAN, it spreads across an area of 100kms to 1000 kms. "A WAN is a data communications network that covers a relatively broad geographic area and that often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer." A simple example for these networks is the network of a huge IT company, which contains branches all over the world with all its branches connected to each other.
Wireless Networks
Wireless Networks are those networks wherein the interconnection between two systems is not physical. The computers that interchange information are not physically linked with wires.
Bluetooth
Bluetooth is a wireless network that has a short range and can be used to connect a system with its internal components like monitor, mouse, CPU, etc without actually having a plug in. Components that support the Bluetooth technology can be detected whenever they are in the detectable range.
Routing
When there are multiple paths between the sender and the receiver the best path for sending the information has to be chosen. The choice is made based on a number of criteria like the number of hops between the systems or on the physical distance between the systems. This process of finding the best path is known as routing.