The Internet and the The Internet and the World Wide WebWorld Wide Web

The Internet and the The Internet and the World Wide WebWorld Wide Web

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 22

What is the Internet?

• A collection of networks (LANS and WANS) around the world that can to communicate with each other

• The physical infrastructure or backbone is made up of:– Computers– Cables– Satellites

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 33

The Global Network

Satellites

Computers

Cables

Servers

Users

ISPs

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 44

WWW Structure

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 55

What is The Word Wide Web (WWW)?

• The URL or web address uses a set of protocols that allows different types of computers and operating systems to ‘talk’ to each other

• The URL is a ‘translating’ device

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 66

Hypertext

• Hypertext is the code used to prepare pages for viewing (HTML tags etc)

• Hypertext links are placed throughout web pages that allow the user to jump from place to place (site to site)

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 77

Browser

• The Browser is the software used to explore the internet– Internet Explorer (Microsoft)– Netscape Navigator (Mark

Andreesen)

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 88

Protocols

• Are the rules followed to communicate over the WWW– http – hypertext transfer protocol– URL – Uniform Resource Locator– FTP – File transfer protocol– TCP/IP – Transmission Control

Protocol/ Internet Protocol

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 99

URL – Uniform Resource Locator

• A URL or Web Address is made up of a number of parts

• It represents the unique address of an internet site or file

http://http://www.intel.com/pressroom/links.htm

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 1010

ISP – Internet Service Provider

• A company that provides access• A monthly fee (or sometimes free) gives

you– The necessary software package– A username and password– An access phone number

• Equipped with a modem, you can then log on to the internet and browse the WWW and send and receive emails

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 1111

Web Server

• This is a very large computer which holds website files

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 1212

HTTP• HTTP (Hypertext Transfer Protocol)

– It transports ‘hypertext’ documents over the internet

– The user enters an address (URL) in the browser, which identifies a file on a web server

– The file is located, sent to the users computer and interpreted by the browser, after which it can be displayed on the screen

http://http://www.intel.com/pressroom/links.htm

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 1313

HTTP

• With HTTP the file itself is not sent to us – only a copy that is held in the browser’s ‘cache’ or temporary memory

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 1414

IP Address• Every computer connected to

the internet needs an IP address– Example (234.208.12.129)

• For intuitive reasons these are often replaced by Domain Names such as intel.com or microsoft.com

http://www.intel.com/pressroom/links.htmpressroom/links.htm

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 1515

The URL

In order to find a particular file the system needs to know the path, folder, and file name of what is being requested (its exact location on the server)

http://www.intel.com/pressroom/links.htmpressroom/links.htm

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 1616

FTP

• We use FTP (File Transfer Protocol) to ‘download’ files from a web server to our own computer

• If we want a permanent copy of a file from the internet stored on our computer we must use FTP

• FTP is also used to ‘upload’ files to a web server

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 1717

Downloading Files

•We need to consider copyright issues before downloading and using files from the internet

•Viruses can infect your computer from downloaded files or emails

•Lots of files - programs, text, graphics, images, even sounds - are available to be copied without restriction

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 1818

TCP/IP

• Transmission Control Protocol / Internet Protocol

• Controls all traffic on the internet• A standard method for transferring

data

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 1919

TCP/IP

• ISPs have fixed IP addresses but ordinary users will have dynamic IP addresses

• A large file is broken up to be transported across the internet

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 2020

TCP/IP - a two-layer program

TCP • Breaks messages into smaller

‘packets’ for transmission• Ensures that all the bits are put

together at the other end

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 2121

IP

IP • Handles the address part of

each ‘packet’ so that it gets to the right destination

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 2222

People

• Tim Berners-Lee– developed the system of hyper-

linking• Mark Andreesen

– developed the first web browser

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 2323

Factors leading to Growth of the WWW

– Fall in cost of computers – Smaller computers– Development of protocols and

standards– Hypertext – clickable links– New web browser software– Growth in networking – LANs and

WANs

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 2424

Uses of Internet

• E-mail• E-commerce/Shopping• Making Bookings (travel)• Research/Education• News• Chat/Entertainment

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 2525

Today

• About 4.3 billion IP addresses at present

• Millions spent every day online• Millions do business and

communicate every day over the ‘net’

Una DooneyUna Dooney The Internet and WWWThe Internet and WWW Slide Slide 2626

Reading

From S: drive•Domain Names•Brief History of the WWW•Lecture NotesComputers – Tools for an

Information Age by H L Capron and J A Johnson Ch 8