Internet meaning definition

1. Internet
By
S. Yesan
Associate Librarian
SAIACS, Bangalore,
E-Mail: yesan@rediffmail.com

2. Introduction
It’s a network of networks
Information superhighway
A World Wide channel of communication
A global network connecting millions of
computers.
Each Internet computer is called “host”

3. Internet Vs WWW
Network of networks Way of accessing
information over the
Internet
Connects millions of
computers
It is an information
sharing model
Any computer can
communicate to each
other through Internet
Uses HTTP to allow
applications to
communicate
Utilizes web browsers
IE, Netscape Navigator

4. Contd.,
Internet is not web It is one of the ways that
information can be
disseminated over net
Relies on SMTP for
email
It is a portion/part of
Internet

5. History of Internet
It was not a planned event
1960’s US needed for a technological
investigation in networking for sharing
defense data
1969 Advanced Research Projects Agency
(ARPANET) unit of DOD
– To test reliable linking computers
– To link DOD and other military research
contractors

6. ENIAC
1946
1950
Batch
mode
1960’s
Interactive
1967
ARPAnet
1947
Transistor 1959
I/C
1838
Telegraph
1876
Telephone
1896
Radio
1923
TV
Satellite
Microwave
1970
Packet
Radio
1976
Ethernet
1979
Cambridging
1971
History of Internet
Computer Network

7. History contd..
ARPAnet was to find out how to
communicate b/w the R* centers & Military
organizations
Formed a small network comprising
– University of California at Los Angeles
– University of California at Santa Barbara
– Standford University
– University of Utah in Salt Lake City

8. History – Contd..
By 1972 over 40 different sites attached to
ARPAnet
Services such as, E-mail, Telnet, FTP
End of 1970’s ARPAnet was grown into
larger network
It was split into two, MILnet, ARPAnet
1979’s CSNET (Computer Science
Research Network) of NSF (National
Science Foundation)

9. Who governs the Net?
No one in particular governs the net
It is based on an agreement b/w different
networks
Internet Society (ISOC) and NSFnet
(National Science Foundation Network)
play significant role in managing the net

10. Internet Society (ISOC)
It has a direct control over the net.
It provides assistance and support to groups and
organisations in the use operation and evolution
of the Internet.
Provides support for forums in which technical
and operational questions can be discussed
Provide mechanisms through which the
interested parties can be informed and educated
the Internet, its function, use operation

11. Components of Internet
Desktop (PC)
Modem
– Converts the digital signals to analog signals
MOdulates and DEModulates
Telephone Connection
Internet Connection (Paid or Free)

12. Internet
Receiver
Sender
Digital Signal
Digital Signal Analog
Analog

13. Types of Connection
Dial-up connection
– Link to Internet is brought about by a dial-up
account given by agency
– Dial up to the Internet Service Provider to
have access to the Internet
– Cheaper than dedicated links
– Affordable by any common man

14. Types of connection
Dial-up connection
– Disadvantages: Speed depends on the
telephone lines
– Slow during peak hours

15. Dedicated Links
Used by larger organisations, institutions,
Govt and Corporate Bodies.
Direct line is established b/w the
organisation and entire network of the
networks.
As result of this organsations computers
become part of the Internet

16. Dedicated Links
Institutions have its own gateways and has
full time direct access to Internet.
Maximum data transfer is possible at a
higher rate/speed
Expensive and can be afforded by larger
organisations

17. Information Services and Sources
Internet
Email
Full Text
Bibliographic
Databases
Web Pages
Chats/Conferences
User 1
IBM/MAC
User 2
Ethernet
User 3
Token Ring

18. Overview of Internet Services
General Services
– E-mail, Telnet, FTP, BBS, Usenet, Chat
Navigation Tools
– Archie, Gopher, WAIS, WWW
Other utilities: Ping, Nslookup, Finger,
Netfind

19. Electronic Mail (E-Mail)
Most economical and highly used modes
of communication.
“Electronic mail, simply is a way for
computer users to exchange messages
b/w different, distant computers as long as
there are networks such as Internet
connecting them”.

20. E-Mail
To send messages to specific individuals
To send messages to many individuals
To send messages to a predefined list of
users
To Send txt files
To send attachments – prgs, graphics,
word processed files, spread sheets,
images and audio-video files
To send Electronic greetings card

21. Working of E-Mail
It is not required that two communicating
computers should be directly connected.
Based on the principle of store and
forward
It is an interactive mode of communication

22. Types of programs in E-Mail
User Agent Program (E-Mail Client)
– Mail reader, provides and manages those
functions that needed to read, write and
manage the E-Mail messages
– Interacts with a corresponding server
– Client prgs: mail, sendmail (Unix), Pine, elm,
eudora (PCs and Macintosh), MS outlook,
Outlook Express (MS Windows)

23. Working of E-Mail
Mail Delivery Agent (E-Mail Server)
– Plays a role of an “Electronic Post Office”
– Client sends messages to this post office and
messages get queued up here.
– Periodically the messages are sent out
– Decides where the message is to be sent
– It also receives mails sent to it from other clients.
– Received mails are queued up here
– The server also forwards messages to the destination

24. Store and Forward Technology
When the mail server receives a message,
it makes a copy (stores it) and then tries to
pass it on (forwards) to the destination
Does not delete its copy until and unless
the next server has acknowledged receipt
of the forwarded mail

25. E-Mail Address
E-Mail address plays major role in
delivering the mail to the right recipient.
Parts of the E-Mail
– User ID
– Fully qualified Domain Name
– The above two are separated by @ (the “at”
sign) separator symbol.

26. E-Mail Address
E.g., library@saiacs.org
– User ID is library
– Domain Name is saiacs.org
– Mail sent to library@saiacs.org will reach a
person/unit “library” on the machine
“saiacs.org”

27. E-Mail address
Convention is followed in assigning E-Mail
address. Based on the type of
organisation, the domain name is usually
assigned.
– Examples
Commercial Organizations : .com
Non Profit Organizations : .org
Research Centres/Orgs : .res or ernet.in
Academic institutions : .ac

28. Conventions codes for countries
India : .in
United Kingdom : .uk
Australia : .au
USA : .us
New Zealand : .nz

29. Components of E-Mail
Content information
– Who, when, where, what
Content
– Body of the message/text
– Attachments, if any

30. Telnet/Remote Login
Allows one to access a remote computer
and work on it sitting at a distant terminal
connected on the Net.
Enables to work and download the results
through FTP
It is an application tool for connecting on to
a remote machine and working on it.

31. Telnet
It works on TCP/IP protocol used to
support remote login sessions
TCP/IP protocol defines how local and
remote computers “talk” to each other in a
remote login session

32. Telnet Working
It is a “client-server” type of application.
Client program interacts with Telnet sever
– %telnet<remote machine name>
User ID or login name :xxxxxxxxx
Password :xxxxxxxxx
Once the given user ID and password are
accepted by the system the user can use
all prgs available on the remote machine

33. File Transfer Protocol (FTP)
It is an application prg used to move files
b/w computers
It is named after the application protocol it
uses which is File Transfer Protocol
It is used for retrieving files from public
archives that are scattered around the Net
Location of computers and how they are
connected is immaterial

34. FTP
Through this the shareware prg files can
be downloaded from Net.
It requires specific address of the machine
with file name
Syntax to ftp get and ftp put commands
– %ftp>get source-file destination file
– %ftp>put source-file destination file

35. For file transfer one needs to know the
exact name of the file that is to be
transferred and also where it is located.
To get file listing is ‘ls’ and ‘dir’
– ftp>dir directory-name local file name
– ftp>ls directory-name local file name

36. Bulletin Board Service (BBS)
It is an electronic message system for
reading and posting messages
Comprised of small groups of users who
have a common interest.
Provides forum to chat on subjects of
special interest to the individuals included
in that BBS

37. Usenet
It is system looking after discussion
groups or chat lines of members who
regularly gather to speak, to exchange
views and comment.
It is a world wide community of electronic
BBSs closely associated with Internet or
the Internet community.

38. Characteristics of Usenet
Information consists of individual
messages, each can be read and shared
by many users.
Messages are organised into topical
groups called as newsgroups
Spl s/ws packages are there to use the
Usenet an to be Usenet site.
Any one can participate in discussions

39. Navigation Tools
Tool to use Internet
Difficult in locating information due to large
amt of information available on web
It is a tool to search and locate the
information
To navigate information

40. Tools for locating net sources
Tools based on the kind of structured
querying.
Each tool accesses its own holdings of
data when a search is made.
– Gopher, Archie, WWW and WAIS

41. World Wide Web (WWW)
A navigation tool on the net, enables
browsing information linked to other
related information.
It is referred to as “WWW”, ‘W3’
Unlike other tools, one need not to know
the site address, machines to access the
information

42. WWW
It is possible to jump from one location to
other through what is called “Hyper-
Linking” of documents
It is not so important to know where to
start as long as we get to know where we
want to be.

43. Resources on the Web
Resources are identified with a special
name called “Uniform Resource
Identifiers/Locators (URL)”
It will describes the protocol needed to
access the web page and access points to
its Internet location and home directory
URLs are address for documents on the
web.

44. WWW
Parts of URL
– Protocol
– Hostname
– Filename
The syntax: protocol://hostname/filename

45. WWW
URL describes what to do when the
hyperlink is activated, to reach the target
server, the hostname and the document
filename
– E.g., http://www.saiacs.orgpublications.html

46. WWW
By using the http protocol to reach a
server called saiacs.org
Besides http, other important protocols are
gopher, telnet and ftp

47. Web Servers
Server with web pages stored
A machine on the network, to recognise and
accommodate web requests
Tasks of web server
– Listening for specific requests for the web resources
that arrive from the network
– Interpreting valid requests as they arrive and
attempting to locate the requested resources
– Providing those resources over the network or giving
an error message explaining why a request can’t be
honoured

48. The storage and retrieval part is handled
by the ‘web server’
Handling of multitudes of information is
possible in client server model.
Accommodates requests for the web
information and defined by the domain
name

49. Networking protocols
Protocols links the clients and servers
address issues handling requests and
responses.
HTTP provides a way of communication
b/w web clients and servers
Server needs web server s/w, HTTP
Client requires a browser s/w –
– Netscape Navigator, Internet Explorer

50. Information exchange on the web
It comes in four parts
– Connection
Client connect to specific web server
– Request
Client asks for a web resource it is looking for.
Includes protocol to be used, the name of the
object to be provided and information about how
the server should respond to the client is also
given

51. Response
– Server delivers the requested object,
information, in a manner requested by the
client
– If the necessary data is not available, an error
message is provided.
Close
– After the response to the request is complete,
the connection b/w the client and server
needs to be closed. Reopened on request.

52. Browsers
A software program that allows to access
the graphical portion of the Internet i.e.,
WWW
NCSA Mosaic – National Center for
Supercomputing Applications.
Two types
– Txt based and GUI (Graphical User Interface)

53. Text Based Browsers
– Lynx: it is basically a text based browser.
Approach is provided through keyboard
interaction.
GUI Based Browsers:
– Very user friendly, allows to access the
multimedia formats online
Netscape Navigator, Internet Explorer

54. Search Engines
It is a program that searches through the
Internet’s data.
In the context of the web, a search engine
is most often used in association with
searching through databases of HTML
documents

55. Components of Search Engines
Robot
– Web wanderers, web crawlers or spiders.
– Traverse the WWW looking for the
information, moves from one web to another
web document by referring to the hyper links.
– It indexes the documents, validates of HTML,
links, monitoring for new information and
mirroring the web

56. Database:
– Records all the indexed information.
– It includes web addresses, titles, headers,
words, first lines, abstracts and full text in its
lists.
– It can store any where from a thousand
millions of web pages.
Agent
– Role b/w original/sources and clients/users

57. Types of Search Engines
Individual Search Engines
Subject Directories
Meta Search Engines

58. Individual Search Engine
Can be full text or non-full text
Robots scan a large part of the web while
designated robots are programmed to scan only
specific sites.
Some cases generally the hits retrieved will be
fewer in number
In other cases, depth-orientated robots search
deep into a document to pull out individual items
and their respective links to other servers.

59. Subject Directories
Hierarchical indexes or directories of
Internet resources may be searched and
browsed.
Focus for providing information is by
subject
Subject directory serves as TOC and
Search Engines are like Indexes of the
book

60. Advantages
– Useful in browsing subject information
Limitations:
– Frequency of updation is less and coverage is
limited to subject.

61. Meta Search Engines
It is Search Engines of Search Engines
It is a combination of a number of Search
Engines.
Advantage is that on submitting a search
query, several search engines perform the
search at a time.

64. Time
Results