Computer Skill II
Module 2
MODULE 2: COMPUTER AND INFORMATION ON THE WEB
(THE INTERNET)
INTRODUCTION
• The Internet (INTERcontinental NETwork) is a worldwide connection of millions of
computer and networks that support Internet Protocols (IP). In order to be really on the
internet, your computer needs to be using the internet protocol. Then you can use
programs like Netscape Navigator, outlook express and the Microsoft internet
Explorer to access the World Wide Web and other internet services. People from
different areas of life are using internet. For instance, business professionals,
government workers, politicians, doctors, teachers, students, researchers etc. - virtually
everyone who wants to succeed in the information society is using the internet.
•
Users of the internet can exchange electronic mail, participate in electronic discussion
forums (newsgroup), send files from any computer to any other via FTP, retrieve
information via Gopher or HTTP, and even use each other’s computers directly via
Telnet or rlogin if they have appropriate passwords.
Protocol
• In the networking, term “Protocol” is defined as a standard way of carrying out data
transmission between computers. The protocol includes TCP/IP; FTP; NETBEUI;
IPX/SPX; ATM and Gopher.
• The TCP/IP(Transmission Control Protocol/ Internet Protocol) is a standard format
for transmitting data in packets from one computer to another. It is used on the internet
and various other networks to governor on how information gets transmitted in packets
over the internet or other network. If the information is too large to fit in a single
packet, multiple packets get sent. TCP takes care of dividing the information into
packets, routing the packets to their destination and assembling the information whet it
arrives. If the packets arrive out of sequence, TCP puts them back together in the right
order. TCP can even detect when errors occurred on the transmission line to alter the
information, in which case TCP asks for errant packets to be transmitted.
• The FTP (File Transfer Protocol) is a standard way of transferring files from one
computer to another on the internet and on other TCP/IP networks. FTP is also the
name of any various computer programmes that implement the file transfer protocol.
• The NetBEUI (NetBIOS Extended User Interface) is a data transmission protocol
developed by IBM and Microsoft and widely used in local area networking. It is
usually the preferred protocol for networking windows systems but does not support
routing.
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© The State University of Zanzibar
2011
Computer Skill II
Module 2
• IPX/SPX (Internetwork Packet Exchange/Sequenced Packet Exchange) is a data
transmission protocol developed by Novell and Widely used in local-area networking.
• ATM: In Banking, abbreviation for Automatic Teller Machine. But in Networking, is
an abbreviation for Asynchronous Transfer Mode, which is a set of high-speed data
transmission protocol.
• Gopher a computer programme, and an accompanying data transfer protocol, for
reading information that has been made available to the public on the internet. Gopher
is supported by the University of Minnesota and uses a menu-driven user interface. It
has mostly been superseded by HTTP (Hypertext Transfer Protocol) and Browser such
as Netscape (which can read Gopher information as well as HTTP information). The
name “Gopher” is a pun on “go for” (i.e go and get things).
•
INTERNET SERVICES
What people do on the internet is organized according to services defined by protocols
that are specifying how information moves across the Net. The most popular protocols
as mentioned earlier include; the World Wide Web (www) electronic mail (e-mail),
listserv, newsgroups, chat, files transfer protocol (FTP), telnet, , and. Gopher
World Wide Web (www)
The World Wide Web (commonly shortened to the Web) is a system of interlinked,
hypertext documents accessed via the Internet. With a web browser, a user views web
pages that may contain text, images, videos, and other multimedia and navigates between
them using hyperlinks. The World Wide Web was created in 1989 by Sir Tim BernersLee and Robert Cailliau, working at CERN in Geneva, Switzerland. Since then, BernersLee has played an active role in guiding the development of web standards (such as the
markup languages in which web pages are composed), and in recent years has advocated
his vision of a Semantic Web.
How the Web works
Viewing a web page on the World Wide Web normally begins either by typing the URL
of the page into a web browser, or by following a hypertext link to that page or resource.
The web browser then begins a series of communications, behind the scenes, in order to
fetch and display it.
First, the server-name portion of the URL is resolved into an IP address using the global,
distributed Internet database known as the domain name system, or DNS. This IP address
is necessary to contact and send data packets to the web server.
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© The State University of Zanzibar
2011
Computer Skill II
Module 2
The browser then requests the resource by sending an HTTP request to the web server at
that particular address. In the case of a typical web page, the HTML text of the page is
requested first and parsed immediately by the web browser, which will then make
additional requests for images and any other files that form a part of the page. Statistics
measuring a website's popularity are usually based on the number of 'page views' or
associated server 'hits', or file requests, which take place.
Having received the required files from the web server, the browser then renders the page
onto the screen as specified by its HTML, CSS, and other web languages. Any images
and other resources are incorporated to produce the on-screen web page that the user
sees.
Most web pages will themselves contain hyperlinks to other related pages and perhaps to
downloads, source documents, definitions and other web resources. Such a collection of
useful, related resources, interconnected via hypertext links, is what was dubbed a "web"
of information. Making it available on the Internet created what Tim Berners-Lee first
called the WorldWideWeb (note the original name's use of CamelCase, subsequently
discarded) in 1990.[1]
Caching
If a user revisits a web page after only a short interval, the page data may not need to be
re-obtained from the source web server. Almost all web browsers cache recently-obtained
data, usually on the local hard drive. HTTP requests sent by a browser will usually only
ask for data that has changed since the last download. If the locally-cached data is still
current, it will be reused.
Caching helps reduce the amount of web traffic on the Internet. The decision about
expiration is made independently for each downloaded file, whether image, stylesheet,
JavaScript, HTML, or whatever other content the site may provide. Thus even on sites
with highly dynamic content, many of the basic resources only need to be refreshed
occasionally. Web site designers find it worthwhile to collate resources such as CSS data
and JavaScript into a few site-wide files so that they can be cached efficiently. This helps
reduce page download times and lowers demands on the web server.
There are other components of the Internet that can cache web content. Corporate and
academic firewalls often cache web resources requested by one user for the benefit of all.
(See also Caching proxy server.) Some search engines, such as Google or Yahoo!, also
store cached content from web sites.
Apart from the facilities built into web servers that can determine when files have been
updated and so need to be re-sent, designers of dynamically-generated web pages can
control the HTTP headers sent back to requesting users, so that transient or sensitive
pages are not cached. Internet banking and news sites frequently use this facility.
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© The State University of Zanzibar
2011
Computer Skill II
Module 2
Data requested with an HTTP 'GET' is likely to be cached if other conditions are met;
data obtained in response to a 'POST' is assumed to depend on the data that was POSTed
and so is not cached.
Electronic Mail (e-mail)
• The Internet system works because of SMTP, Simple Mail Transfer Protocol. SMTP is
part of the TCP/IP suit of protocols.
• SMTP is a protocol, or set of rules that enables electronic mail to move smoothly
through the internet. Because of SMTP, a UNIX machine can send mail to a PC or
Macintosh computer and vice versa.
•
•
•
Electronic mail has revolutionized the way people communicate when they can not
talk in person. No longer must people wait for traditional postal mail delivery. On the
internet, if both the sender and the receiver log on frequently, it is possible to exchange
several messages with someone in a single day.
You can communicate with anyone in the world who has an internet address or email
account with a system connected to the internet. All you need is access to the internet
and an e-mail program.
A Typical e-mail message has three basic elements; header, message, and signature.
• (a) The header appears first and typically includes the following information:
•
Subject: A one-line description, used to present the topic of the message.
Subject lines typically are displayed when a person checks his or her mailbox.
•
Addresses: addresses of the persons sending (to:), receiving (from: ), and,
optionally, anyone else who is to receive copies (CC and BCC).
• Attachments: Many e-mail programs allow you to attach files such as documents and
worksheets. If a message has an attachment, the file name appears on the attachment
line.
• (b) The letter or message comes next. It is typically, short and to the point.
• (c) Finally, the signature line provides additional information about the sender.
Typically, this information includes the
•
sender’s name, address, and telephone number.
•
E-MAIL ADDRESSES
The Internet uses an addressing method known as the Domain Name System (DNS) to
assign names and numbers to people and computers. This system divides an address
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© The State University of Zanzibar
2011
Computer Skill II
Module 2
into three parts: user name (ID), domain name, and domain code. Fore example
takiluki@zanlink.com: user ID is takiluki, domain name is zanlink and com is the
domain code which is commercial.
•
The domain code identifies the geographical description or organizational
identification.
Almost all ISPs (Internet Service Providers) and online service providers offer e-mail
service to their customers. But you can get this service for free from different service
providers such as Hotmail, USA Net Inc., and Yahoo. To lean more about free e-mail
service, visit one or more of the following sites: http://www.hotmail.com,
http://www.usa.net, mail.yahoo.com etc.
LISTSERV (List Server)
It works like electronic mailing lists, sending e-mail messages to people whose names are
on the list. You join a listserv by emailing a message to it, saying that you want to
subscribe. Then, whenever someone sends e-mail to the listserv, you will receive a copy
in your e-mail. Likewise, when you send e-mail to the listserv, everyone on the listserv
will get a copy of your message. I you want to cancel a mailing list, send an email request
to “unsubscribe” to the subscription address. Thus listserv is a simple way for groups of
people to communicate with one another through e-mail.
NEWSGROUP
Newsgroups are widely type of discussion group. Unlike mailing lists, newsgroup use
special network of computers called the UseNet. USENET is an electronic bulletin-board
service consisting of newsgroups, news feed and newsreaders. Once you subscribe to a
newsgroup, you use a newsreader to access the group’s news feed. In addition to reading
information on existing topics, you can add your comments and create new topics,
thereby participating in virtual conference on the internet.
CHAT
Chat groups are becoming very popular type of discussion group. It is a very popular
form of real-time communications on the internet is Internet Relay Chat (IRC). While
mailing lists and newsgroup rely on email, chat groups allow direct “live”
communication. To participate, you join a chat group, select a channel or topic, and
communicate live with others by typing words on your computer. Other members of your
channel or group immediately see those words on their computers and can respond in the
same manner.
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© The State University of Zanzibar
2011
Computer Skill II
Module 2
INSTANT MESSAGING
Like a chat groups, an instant messaging allows one or more people to communicate via
direct, “live” communication. Instant messaging, however, provides greater control and
flexibility than chat groups.
To use instant messaging, you specify a list of friends, or “buddies”, and register with an
instant messaging server. Whenever you connect to the internet, you use special software
to tell your messaging server that you are online too. It notifies you if any of your buddies
are online. At the same time, it notifies your buddies that you are online. You can then
send messages back and fourth to one another instantly.
FINDING THINGS ON THE INTERNET
•The internet is the richest source of information on the planet. Just about anything you
could ever want to know is available online. Especially for students and scholars
conducting research, the internet is a fantastic resource for finding out what’s been done
in your field.
Searching for Information
•The key factor of doing the research potential of the internet is to know how to use the
search engines. Then using either subject-oriented searching or key word searching.
•Search engine is a computer programme that searches through large amounts of text or
other data. For example, a search engine for the world wide web are: www.yahoo.com;
www.search.cnet.com, www.altavista.digital.com; www.google.com; www.excite.com;
www.infoseek.com.
Subject-Oriented Searching
•When you search a topic, it is wise to begin by conducting a subject-oriented searching.
This will tell you how much information is available about your topic as a subject and
others have written about. The subject-oriented search engines use a combination of
human beings and robots (known as spider) that search the web continually, organizing
what’s found into hierarchical index of topic. When you conduct a subject-oriented
search, the search engines searches this index and provide you with a list of item related
to your topic. To retrieve the item, you simply click it with your mouse.
Key Word Searching
•Like subject-oriented search engines, key word search engines have “spider” that
constantly combining the web and feeding the information into the database. Instead of
organizing the web according to the subject areas, however, key word search engines let
you search for the key word in documents regardless of the “subject” of the documents.
Therefore, key word search engines are likely to find more than subject-oriented search
engines, but what’s found may not be relevant to your subject.
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© The State University of Zanzibar
2011