Page 13 - M. Abrahim Thesis

Computer Network 2021

To human beings, radio, microwaves, radar, visible light, X rays, and gamma rays seem to
be very different things, but they are all types of electromagnetic energy. If all the types of
electromagnetic waves are arranged in order from waves with the longest wavelength down to
those waves with the shortest wavelength, it creates a continuum called the Electromagnetic
Spectrum.
https://www.youtube.com/watch?v=pj_ya0e20vE&t=40s

1.2 The Fundamentals of Internet Connectivity

To understand the role that computers play in a networking system, consider the
Internet. The Internet can be thought of as a tree with computers as leaves. Computers are the
sources and receivers of information by way of the Internet. Computers can function without the
Internet, but the Internet cannot exist without computers. The Internet is growing rapidly, and
users are becoming increasingly dependent on it for a myriad of services. Computers, along with
being an integral part of a network, also play a vital role in the world of work. Businesses use
their computers for a variety of purposes, but they also use them in some common ways. They
use servers to store important data to manage customer and employee accounts. They use
spreadsheet software to organize financial information, word processor software to maintain
records and correspondence, and browsers to access internal and external websites. High-speed
accesses to the Internet, such as cable modem and DSL services, are now available to the home
and small office, which is increasing the demand for support services. No longer satisfied with a
single computer connected to the Internet, the consumer needs the tools to be able to share the
connection. The Internet is the largest data network in the world. The Internet consists of a
multitude of interconnected networks, both large and small. At the edge of this giant network is
the individual consumer computer.

Connection to the Internet can be broken down into the following components:

• The physical connection—A physical connection to a network is made by connecting
a specialized expansion card, such as a modem or a network interface card (NIC), to
a PC with a cable. The physical connection is used to transfer signals between PCs in
the local network and remote devices on the Internet.

• The logical connection—The logical connection uses standards called protocols. A
protocol is a formal description of a set of rules and conventions that govern how
devices on a network communicate. Connections to the Internet may use multiple
protocols. The Transmission Control Protocol/Internet Protocol (TCP/ IP) suite is the
primary protocol used on the Internet. TCP/IP is a suite of protocols that work
together to send and receive data.
• Applications—The application that interprets the data and displays the information
in a comprehensible format is the last part of the connection. Applications work with
protocols to send and receive data across the Internet. A web browser displays HTML
as a web page. File Transfer Protocol (FTP) is used to download files and programs
from the Internet. Web browsers also use proprietary plug-in applications to display
special data types such as video, audio, and animation.

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