Introduction

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* Data communication is the transfer of data from one device to another via some form of transmission medium.

* A data communications system must transmit data to the correct destination in an accurate and timely manner.

* The five components that make up a data communications system are the message, sender, receiver, medium, and protocol.

* Text, numbers, images, audio, and video are different forms of information. 

* Data flow between two devices can occur in one of three ways: simplex, half-duplex, or full-duplex.

* A network is a set of communication devices connected by media links.

* In a point-to-point connection, two and only two devices are connected by a dedicated link. In a multipoint connection, three or more devices share a link.

* Topology refers to the physical or logical arrangement of a network. Devices may be arranged in a mesh, star, bus, or ring topology.

* A network can be categorized as a local area network (LAN), a metropolitan-area network (MAN), or a wide area network (WAN).

* A LAN is a data communication system within a building, plant, or campus, or between nearby buildings.

* A MAN is a data communication system covering an area the size of a town or city.

* A WAN is a data communication system spanning states, countries, or the whole world.

* An internet is a network of networks.

* The Internet is a collection of many separate networks.

* TCP/IP is the protocol suite for the Internet.

* There are local, regional, national, and international Internet service providers (ISPs).

* A protocol is a set of rules that governs data communication; the key elements of a protocol are syntax, semantics, and timing.

* Standards are necessary to ensure that products from different manufacturers can work together as expected.

* The ISO, ITU-T, ANSI, IEEE, and EIA are some of the organizations involved in standards creation.

* Forums are special-interest groups that quickly evaluate and standardize new technologies.

* A Request for Comment (RFC) is an idea or concept that is a precursor to an Internet standard. 

Reference:

Data Communication and Networking
Fourth Edition

Behrouza A. Forouzan