Transcript Introducing the Internet

Introducing the Internet
Source: Learning to Use the Internet
Introducing the Internet
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A Description of the Internet
Internet Services and Tools
How the Internet Works
How the Internet Developed
Explanation of Internet Domain Names and
Addresses
A Description of the Internet
The Internet is:
• millions of people communicating
electronically on a one-to-one basis or in
groups to share ideas and information.
• a vast collection of information on a wide
variety of topics that can be searched and
retrieved electronically.
A Description of the Internet
(Cont.)
• A network of tens of thousands of computer
networks that connect over a million
computer systems. These networks
communicate by exchanging data according
to the same rules, but they may be using
different technologies.
Internet Services
• Electronic Mail (e-mail)
• Telnet
• FTP
Electronic mail (e-mail)
• Lets you send and receive messages in electronic
form.
• These messages can be text, spreadsheets, wordprocessing documents, images, programs, etc.
• Can join interest or discussion groups and mailing
lists.
• Example of an e-mail address:
[email protected] where somebody is the
user name, lib.umich.edu is the domain name of
the site used.
Telnet
• Allows you to connect and log into a remote
computer.
• You can use it to access any of the public
services or tools at the remote site.
• Can be used for access to libraries,
databases, or other Internet services.
FTP
• File Transfer Protocol
• Lets you transfer files from one computer
on the Internet to another.
• Using anonymous FTP one can retrieve files
without being a registered user on another
computer system.
Internet Tools
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Hytelnet
Archie
Gopher
WAIS
World Wide Web (WWW)
Hytelnet
• A tool for working with Telnet.
• Using Hytelnet you may get an organized
collection of sites and services available
through Telnet.
• You browse the collection using a hypertext
interface.
Archie
• Lets you search the archives of files
accessible by anonymous FTP.
• Search is done using the complete or partial
name of a file and the answer is the Internet
address and location of files.
Gopher
• A menu-based document delivery system.
• Provides access to information such as files,
documents, address books, and images.
• Also allows access to ftp, telnet, and
searchable databases.
• Veronica is a tool to search Gopher menus
for resources throughout the Internet.
WAIS
• Wide Area Information System
• A system for searching and retrieving items
from databases.
• Search is done using one or more keywords.
The result is a list of articles arranged in a
list. These articles you can view on the
screen, save to a file, or send to an Internet
address via e-mail.
WWW
• World Wide Web
• A single means of access to almost everything
available through the Internet: services, resources,
tools, and information.
• Gives hypertext, and hypermedia access (i.e. links
to other pages, documents, etc.)
• Programs that work with the WWW are the
Internet Explorer, Netscape Navigator and before
these Lynx, and the Mosaic.
How the Internet Works
• The Internet is a network connecting thousands of
other computer networks.
• Each network has a unique address, and each
computer connected to a network has its own
address. Examples of addresses: 194.65.245.76
or sage.my.edu.
• Computer systems within one network can
exchange information with computers on other
networks.
How the Internet Works (Cont.)
• The rules that govern this form of communication
are called protocols.
• Two protocols used are Internet Protocol (IP) and
Transmission Control Protocol (TCP)
• Packets of characters (bytes), with the receiver’s
address, carry information on the Internet. These
packets are passed from one network to another
until they reach their destination. --> The Internet
is a packet-switched network.
How the Internet Works (Cont.)
• The networks on the Internet use a hardware
device called router to communicate with other
networks.
• The router accepts packets addressed to it and
passes on packets addressed to other networks.
How the Internet Developed
• In the late 1960s the United States Department of
Defense funded the ARPANET project.
• ARPA (Advanced Research Projects Agency).
• ARPANET linked researchers at universities,
research laboratories, and some military labs.
• NSFNET was developed to connect
supercomputer centers in the United States.
• The network kept expanding with more and more
computer connections in U.S. and overseas.
How the Internet Developed
(Cont.)
• Other commercial networks and free-nets were
developed.
• The Internet has grown very rapidly into
something that involves millions of people
worldwide.
Internet Domain Names and
Addresses
• An address is assigned to each network, and each
computer within a network gets an address based
on the network’s address. Example:
195.65.245.76
• From left to right, a first group of numbers
identifies a network (e.g. 195.65.245), and a
second group a specific host or computer system
(e.g. 76). This numeric address is called an IP
(Internet Protocol) address.
Internet Domain Names and
Addresses (Cont.)
• Domain names may be assigned to the numbers in
the IP address. Example: sage. myu.edu where
sage is the computer name, and myu.edu the
network name. The last 3 characters (edu, com,
gov, mil, net, org) usually denote the type of
organization.
• Documents are retrieved from the WWW using a
URL (Uniform Resource Locator) address.
Internet Domain Names and
Addresses (Cont.)
• Example of a URL address:
http: www.ee.ic.ac.uk/misc/country-codes.html
• General form of a URL address:
service://domain-name-of-site-supplyingservice/full-path-name-of-item
(http stands for hypertext transport protocol)