INTERNET & E-MAIL
INTERNET
Internet, also called the Net, is an electronic communication device. It is
one of the largest networks that links millions or trillions of computers all
over the world. You can access this network via communication devices and
media such as, modems, cables, telephone lines and satellites.
No one knows exactly how many computers are connected to the Internet.
It is certain, however, that these numbers are in millions and are increasing
at a rapid rate.
The ernet offers many conveniences at your fingertips. You can send
messages to others, meet new friends, bank, invest, shop, fill prescriptions,
file taxes, take a course, play a game, listen to music, or watch a movie.
Internet
The advantage of the Internet is that you can use it from a computer
anywhere: at home, at work, at school, or at a restaurant.
With the help of Internet, you can send a message or even talk to your friend online, no matter
where he is, he only needs to have a computer with an Internet connection.
The Internet consists of many local, regional, national and international networks. Although each of
these networks on the Internet is owned by a public or private organization, no single organization
owns or controls the Internet. Each organization on the Internet is responsible only for maintaining its
own network
At present, more than 500 million people are using Internet for various reasons. The most striking
feature of the Internet is that it can be accessed from a computer from anywhere, i.e., from home,
school, restaurant or even from office.
Success today in the business world requires an understanding of the Internet. Without it, you are
missing a tremendous resource for goods, services, information and communic tions.
Some of the things one can do on the Internet are communicate with others around the world,
banking, investing, shopping, download and listen to music, watch movies, take a course, access
educational material, access sources of entertainment and leisure such as online games, magazines
and vacation planning guides, access other computers and exchange files, share and edit documents
with others in real time, provide information, photographs, audio clips, or video clips.
HISTORY OF INTERNET
Now let us briefly trace the footprints of the Internet in the sands of time.
It all started in the Pentagon, the US Department of Defense. A networking project called ARPA or
Advanced Research Projects Agency was launched, which was to work as a network that would allow
scientists and military personnel to exchange information in a war scenario without disruption in
communications. This network, called ARPANET, became functional in September 1969, linking
scientific and academic researchers in the United States. As researchers and others realized the great
benefit of using ARPANET's electronic mail to share information, ARPANET underwent phenomenal
growth. By 1984, ARPANET had more than 1,000 individual computers linked as hosts. Internet, the
outgrowth of ARPANET today attracts hundreds of millions of hosts.
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Researchers and academics in other fields began to make use of the network. In 1986, National
Science foundation (NSF) connected its huge network of five supercomputer centers, called NSFnet, to
ARPANET. This configuration of complex networks became known as the Internet,
Until 1995, NSFnet handled the bulk of the communications activity, or traffic, on the Internet. In
1995, NSFnet terminated its network on the Internet and returned to its status to that of a research
network.
The traffic on the net is handled by a variety of corporations, commercial firms, and other companies
who provide networks. These networks, along with telephone companies, cable and satellite
companies, and the governments contribute towards the internal structure of the Internet.
The Internet is not bound by any government. It is a huge independent cooperative. Although no
single person, company, institution, or government agency controls or owns the Internet, several
organizations contribute towards its success by advising, defining standards, and addressing other
issues. The group that oversees research and sets standards and guidelines for many areas of the
Internet is the World Wide Web Consortium (W3C).
HOW INTERNET WORKS?
Computers connected to the Internet work together to transfer data and information around the
world using servers and clients. The computer which is responsible for the management of the
resources i.e. programs and data, on a network by providing a centralized storage area is called server.
The computer which has an access to the contents of the storage area on the server is called a client.
On the Internet, a client which can access files and services on a number of servers is called a host
computer. Your computer is a host computer.
The inner structure of Internet resembles the transportation system. In the transportation system,
maximum load of traffic is carried out through the highways, which are linked to the major cities,
Similarly, on the Internet, there are certain main communication lines which carry the maximum load
of the traffic. These communications lines are referred to collectively as the Internet backbone.
The Internet is a packet-orientated network. It means that the data you transfer is divided in packets.
So what happens when you transfer data across the Internet's various networks? The networks are
linked by special computers, called routers.
A router checks where your packet (your data) goes and decides in which direction to send it. It is not
possible that every router is linked with every other router, they just decide on the direction your
data takes. So if the routers know where the data is going, there must be some kind of an address
which is known as the IP (Internet Protocol). The data transferred with IP is divided in packets. This is
handled by another protocol, the TCP (Transmission Control Protocol).
It was soon discovered that the IP addresses (that are, in fact, just numbers) are of course easy to
handle for computers, but not for us as humans. So the Domain Name System (DNS) was introduced
in 1984. The domain name is the location of the person's account on the Internet.
INTERNET ADDRESSES
Just like the postal system, the Internet uses an addressing system to send data to a computer at a
fixed or specific destination. An IP address (Internet Protocol Address) is a unique address that
computer uses in order to identify and communicate with other computer on a network utilizing the
Internet Protocol standard (IP).
50. Dynamic Memory Computer Course
The IP address has four groups of numbers and is separated by a period (.). The number varies between
O and 255. For instance, the numbers 155.27.34.10 are an IP address. Generally, the first part of the IP
address identifies the network and the last portion identifies the specific computer.
It is difficult to remember and use these all-numeric IP addresses. Hence, the Internet favors the use of
a text name that represents one or more IP addresses,
The text version of an IP address is the domain name. The components of a domain name are
separated by periods just like an IP address. Every domain name contains a top-level domain (TLD)
abbreviation that identifies the type of organization which is associated with the domain. Dot com is
the name sometimes used to describe an organization that has a TLD of com.
The domain name system (DNS) is the system on
the Internet that stores the domain name
their corresponding IP addresses. Each time you
specify a domain name, an Internet server (called
the DNS server) translates the domain name into its
associated IP address, so data can route to the
correct computer
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