Internet

1
Internet

• Unit 1
• Introduction

2
Internet

• The Internet is a world-wide network composed of
  thousands of smaller regional networks scattered
  throughout the globe.
• A common set of communication protocols enables
  computers connected to the Internet to
  interchange information with each other.
• On any given day it connects tens of millions of
   users located all over the world.
• Over the last 25 years, the Internet has grown to
  include government and educational institutions,
  and, more recently, commercial organisations.

3

• All types of computers make up the hardware
  connected on the Internet.
• They vary from PCs, Macintoshes and UNIX
  workstations to minicomputers, mainframes and
  supercomputers.
• The Internet gives access to electronic
  libraries, exchange ideas, read the news, post
  questions with newsgroups, examine the weather
  (from reports or satellite photos), obtain the
  latest stock market prices and currency exchange
  rates, and access public government information
  on trade, laws, research and other subjects.

4

• It has been estimated that in the UK about 50 of
  homes have some form of Internet access  and it
  is likely that in the very near future a
  dedicated Internet connection in your house will
  be no more unusual than an ordinary telephone
  line.
• For many businesses the Internet is already a
  vital tool.

5

• The Internet is used for transferring information
  between computers.
• For example,
• E-mail is a convenient, quick and cheap
  alternative to the postal system for business and
  personal correspondence
• File Transfer Protocol (FTP) allows large amounts
  of information to be transferred between two
  computers very conveniently
• Usenet, the world-wide collection of interest
  groups, or Newsgroups, allows groups of people
  with similar interests to exchange views and
  information.

6
World-Wide Web

• Abbreviated to the Web and WWW, this is the
  fastest growing Internet service and, along with
  e-mail, the most widely used.
• The World-Wide Web provides a means of accessing
  and transferring information in the form of web
  pages.
• The World-Wide Web uses the Internet for the
  transmission of web pages and other documents
  between computer users connected to the Internet.
  
• Accessing web pages does not require any
  particular machine or operating system.

7

• Using the Internet, hundreds of thousands of
  people around the world are making information
  available from their homes, schools, colleges and
  workplaces.
• With the aid of Web browsers, the WWW has changed
  the way people view and create information.
• The first true global network, it is
  revolutionising many elements of society,
  including commerce, politics, and literature.

8
WWW search engines

• To access this huge bank of information, spread
  over the entire world, and locate specific
  information on a certain subject, there are
  numerous information retrieval utilities which
  provide access to databases of Web page details.
• These search engines allow Web users to enter
  search criteria in the form of keywords or
  phrases and they retrieve summaries of all
  database entries satisfying the search criteria.
• Of the many information retrieval services
  available, some of the most well known include
  Google, Excite,  Lycos and Yahoo.

9
Web browsers

• The program that you are using to read pages over
  the Internet is called a browser.
• Browsers  help users to access the information
  available on the WWW.
• By using a browser, you simply move from site to
  site by clicking on links in web pages.
• Two well-known browsers are Netscapes Navigator,
  and Microsofts Internet Explorer.
• There is usually a toolbar at the top of the
  screen which contains buttons that perform
  frequently used operations, i.e. for moving
  forwards and backwards through web pages.

10
E-mail

• The most used application of the Internet is
  electronic mail, e-mail.
• It is used to send and receive text-based
  messages such as personal or business letters,
  orders, reports and statements.
• To use Internet e-mail, access to a computer
  which is connected to the Internet and has e-mail
  software is required.
• Most commercial Internet service providers
  include e-mail facilities in their subscriber
  services.

11

• Subscribers are given an identifying code called
  an e-mail address.
• The service provider collects and forwards mail
  sent from that address and holds mail to be
  received by that address until able to deliver
  it.
• The service provider thus acts like a post
  office, and in fact there is a close analogy
  between the way which e-mail is implemented and
  the traditional manual postal system.
• The same principles apply to e-mail users who do
  not rely on commercial service providers -
  messages are automatically forwarded from users
  to their destinations and incoming mail is stored
  on their service providers computer until the
  user is able to accept it.

12
Using a browser

• The single most important type of software used
  on the Internet is the browser.
• A browser provides a friendly interface between
  users and the complexities of accessing
  information and using services on the Internet.
• Browsers help users to navigate through the Web,
  to transmit and to receive information from other
  users or information providers.
• By using a browser, you not have to know the
  format and location of the information you
  simply jump from site to site by clicking on
  hypertext links.

13

• Text links are usually underlined or change
  colour when you move the mouse pointer over them.
  
• Usually the mouse pointer changes from an arrow
  or text cursor to a pointing finger when moved
  over a link.
• Links can also be images that change into
  different images when the mouse pointer is moved
  over them. These are called rollovers and are
  very common on web pages.

14
Browser features

• The image shows the Menu Bar, Standard Buttons
  and Address Bar of IE.
• The Address Bar contains  the URL of a remote
  site, www.aikido.co.uk.

15

• The Menu Bar provides access to all of the
  browsers features.
• The Standard Buttons are as follows
• Previous page (Back).
• Next page (Forward).
• Refresh.
• Home.
• Search.
• Favorites.
• History.
• Mail.
• Print.

16

• The Address Bar allows you to type in the address
  of a site that you want to visit with the
  browser.
• For example, if you typed in www.altavista.com
  you would be connected to a search engine site.

17

• An alternative method of specifying addresses to
  the browser is through the File menu.
• The File gt Open menu also allows you to enter the
  URL you require, but you can also use it to
  browse through your local hard drive for a web
  page that you want to view.