What is the Internet?
The Internet is the name of a worldwide
network of networks that interconnects computers ranging from the simplest
personal computers to the most sophisticated mainframes and supercomputers.
The word "Internet" does not define what is done over these computer
connections--it is just the name of this wide connection itself.
The Internet is huge. No one is exactly sure
just how huge, but there are millions of connected computers.
What is the Internet used for?
The Internet contains the electronic
equivalents of conference rooms and cafes, libraries and bookstores, post
offices and telephones, radio and television stations, newspapers and
magazines, and a growing variety of services that have no counterparts in
the real world.
No matter how humble your own computer might
be, if it is connected to the Internet you can access the resources of
thousands of computers throughout the world. With an Internet connection you
can:
- access online library catalogs,
- copy computer files or software from
archives,
- access databases,
- obtain free electronic books,
- communicate with other people,
- listen/watch remote radio/TV stations,
- access remote computer sites.
Although the Internet is made up of many
diverse computers, together they work like one worldwide computer system.
Who Runs the Internet?
The Internet is an entity with millions of
users and millions of hosts. It has no true central organizing body or even
what may be called a true organizing principle. No owner, No boss!
How does the Internet work?
Over the Internet, the bottom line of all your operations can be summarized
as sending and receiving information with your computer. In many cases, you
would make a connection to a remote computer, and start communicating with
that computer, sending and receiving data. Generally your information will
travel through many computers between you and the computer that you
communicate with. Through many kind of wires, this information transfer is
done very rapidly, without bothering you at all with any of the details.
Communication Protocols
During these communications, as all the computers on the Internet need to
understand what the others want, we need a common global language that these
computers can all speak. These type of languages, or rules for
communication, are called communication protocols. The basic communication
protocol utilized on the Internet is called TCP/IP (Transmission Control
Protocol/Internet Protocol). This would show itself to us as a small
computer program (or driver) that needs to be loaded on our computer in
order for us to access the Internet.
Domains and Addresses
Every computer that communicates over the
Internet, both our computers and the computers that we contact and get
information from, has to have an address that enables outgoing and incoming
messages to find and reach them. As this addressing and message routing is
managed by the IP part of the TCP/IP protocol, they are called IP addresses. An IP address
is comprised of four sets of numbers or octals and are connected with periods (an example is
137.151.1.1). The numbers can be between 0 and 255.
Whenever you want to contact a certain site on
the Internet, you have to provide its address. As the numerical addresses
are too hard to remember, for frequently used Internet sites, we also have
human-friendly names, called "DNS (Domain Name Server) addresses" or "domain
names". A DNS address is of the form:
servername.domain
A typical DNS address could be "help-net.com",
where "help-net" is the server name, and "com" is the domain name.
Sometimes you will also see a protocol name preceding the DNS address, such
as http://www.help-net.com/, or a file name following the computer address,
such as ftp://home.netscape.com/index.html. In some cases, the page you
access may be in a subfolder, as in http://www.help-net.com/computer buddies/index.htm,
where http://www.help-net.com/ is the server, index.htm is the web page, and /computer
buddies
is the folder on this server where this page is located.
There are several different types of domains,
named according to their organizational roles:
com |
commercial organizations |
edu |
educational and research institutions |
gov |
government agencies |
mil |
military agencies |
net |
major networks centers |
org |
non profit organizations |
Domain names may also include country codes at
their end, except for those registered in the USA. Some countries implement
the organization type part of the domain name differently; for example,
commercial organizations in the U.K. use "co" extension instead of "com",
and those in Germany do not have an organization type part at all.
How do computers communicate?
The Internet is constructed with the
philosophy that every computer should be able to communicate with any other
one. However, with millions of computers that make up the Internet today, it
is obvious that a separate physical direct connection from each computer to
all others is impossible.
The Internet is comprised of many smart devices
called routers, whose job is to route the incoming data traffic towards its
destination address. When your computer issues a request (for example, asks
for a web page), that request packet is delegated to the nearest router.
This router looks at the destination IP address, decides on a line in the
direction of the destination, and sends the packet to the next router at the
end of that line. The receiving router acts the same way, and so does the
next one--until the packet reaches its destination. The response to this
request (the web page) travels backwards exactly in the same way.
There may be just one, or there may be 50
routers between two computers that want to communicate over the Internet.
The users will not know this number, and the TCP/IP infrastructure will take
care of the transmission and reception of data packets silently.
How are routers interconnected?
Routers are often placed at the end of
high-capacity long transmission media, to handle incoming and outgoing data
traffic. The transmission medium between any two router could be copper or
fiber-optic cables, radio links, satellite links, etc.
The system of inter-connected high capacity
routers and the data network is called the Internet backbone. Internet
backbones are systems of very sophisticated routers and high-bandwidth data
transmission lines that serve the data connection requirements of a
relatively large geographical region. They are generally built by big
telecommunication companies around the world.
This backbone connects all Internet users around the country, and also
provides access to Internet backbones of other countries through satellite
and fiber-optic links.
How do computer users reach the Internet
backbone?
The big telecommunication companies are (ideally) analogous to a wholesaler
who sells its services to a retailer (your ISP). The retailer, in turn, sells the
service to the end-users (computer users who want to access the Internet
from their homes or offices). However, some of the big telecommunication
companies have lately entered the retail
market itself, and is providing Internet access to end-users in various
forms.
The retailers of the big telecommunication
companies, who provide Internet
access to us are called Internet Service Providers (ISP). Most ISPs also
have their own satellite connections to provide faster access to sites and
computers that are abroad. AT&T, AOL, BellSouth, Earthlink, Road Runner, are
some of the ISPs in our country.
There are also other organizations which act
as service providers in a different sense. For example, most universities
and colleges provide a
special Internet backbone for academic institutions; it connects
universities to one another.
Many institutions act like an ISP to their
computer network users, providing Internet connection to all networked
computers.
What do we need to connect to the Internet?
In order to connect to the Internet, you would
normally need the following things:
A computer
TCP/IP protocol loaded on the computer,
A data transmission means (phone line, ADSL, or Cable)
Hardware that connects your computer to the
data line (Modem),
An ISP
If you would like to connect to the Internet
from home or from your small business, there are a variety of alternatives:
Dial-up Connection
This scenario involves the use of a normal
telephone line to connect to the Internet. Over the telephone, the computer
calls an ISP phone number, which connects us to the Internet. The maximum
data speed is 56 kb/sec, which can be lower due to line quality
problems.
The requirements for this type of connection are:
A computer,
TCP/IP protocol,
A telephone line,
A modem, to convert the digital computer
signals to sound signals, and vice versa,
A user account with an ISP.
Most users rent connection time from an ISP
to connect to the Internet. This involves calling a local phone
number in most cases. You should call as many ISP's in your area to
find out local rates and limitations.
Some ISP's do not charge a monthly
fee. Their service is offered to you at no charge but they flood the
screen with adds. For a small fee $8.00 to $15.00 per month they
will provide a add free connection. If you only use the Internet for
E-Mail the free services are hard to beat.
Cable TV connection
If you have a cable TV connection at your
home, getting Internet connection service over that cable is possible. It
provides two-way communication (information flowing from and towards the
Internet) at asymmetrical rates. You are billed monthly and this enables you to stay
online 24 hours without any extra charge. It requires a network interface
card and a cable modem. The requirements for this type of connection are:
A computer,
TCP/IP protocol,
Subscription to the cable TV service,
A network interface card,
A cable modem,
A user account with an ISP.
ADSL connection
This service is a high speed
connection over standard telephone cable pairs, it provides asymmetric connection.
This will you allow you to use your phone and the computer at the same
time. The
price rates for ADSL are about the same as for an extra phone line.
With this type of connection you get your modem line and Internet access with one monthly
payment. You get 24-hour
connection, and can stay online round the clock at no extra charge. It requires a special modem.
The requirements
for this type of connection are:
A computer,
TCP/IP protocol,
An ADSL line (a telephone cable connected to
an ADSL circuitry on the phone systems equipment),
An ADSL modem,
A user account with an ISP.
Dish Satellite Connection
If you have a dish satellite you might
also be able to use this for the connection at your home. Getting Internet connection service over that
is possible. It
provides two-way communication (information flowing from and towards the
Internet) at asymmetrical rates. You are billed monthly and this enables you to stay
online 24 hours without any extra charge. It requires a network interface
card and a satellite modem. This can be used when you are too far from
the telco switching office or do not have cable in your area.
The requirements for this type of connection are:
A computer,
TCP/IP protocol,
Subscription to the satellite TV service,
A network interface card,
A satellite modem,
A user account with an ISP.
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