Data communications are 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.

data communication

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.


point to point line configuration

point to point line configuration-2

point to point line configuration-3

Multi point Connection
multipoint line configuration

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

network topology


Hybrid Toplogy


Ring toplogy


bus toplogy


tree toplogy


star toplogy


mesh topology

A network can be categorized as a local area network or a wide area network.

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

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.

There are local, regional, national, and international Internet service providers.

A protocol is a set of rules that govern 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, ITD-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

A Request for Comment is an idea or concept that is a precursor to an Internet

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