The Internet

Objectives:Gain an overview of what the internet and the world wide web are.Understand what you need to access the internet.Gain an overview of how it works.

What is the Internet?

The Internet is a network of networks that connects governments, people and companies all over the world.

10 Downing Street, London, England Sydney Opera

House, Australia

Jim’s Skateboards

USA,Patel’s Fine Silks,

India

The Internet

Koji Araki, Japan

A Brief History 1967: APRA (the Advanced Research Projects Agency) at the

US Department of Defence created the ARPAnet: a computer network resilient enough to withstand nuclear attack which would allow the military to communicate in the event of war.

1971: Email is used on the ARPAnet for the first time and its inventor is astonished to discover that it quickly accounts for over 50% of traffic on the network.

1974: The Transmission Protocol Program (TCP) is invented but it is not until 1982 that the Internet Protocol (IP) is added to create TCP/IP - a development which might not sound exciting but it is this protocol which, today, still allows computers to communicate with each other over the Internet.

1976: The Queen sends her first Email, 17 years before the Whitehouse goes on-line for the first time.

1989: The World Wide Web is invented in the UK by an Oxford undergraduate called Tim Brenners-Lee. The WWW proves to be the "killer application" needed to make the Internet truly popular.

1990: The ARPAnet ceases to exist. Long live the Internet!

2000: Around 200 million people using the Internet and rising

A Brief History

Uses of the Internet

•Business

•Research

•Pleasure

•People can communicate in different ways with people all over the world.

Computer signals are and normal telephone lines are , so you need an . if you are using an analogue telephone line. This is called a ( dulator/ odulator).

How does it work?

When you to the Internet you connect your computer to an This is done through telephone or cable services.

digital

connectInternet Service Provider (ISP).

analogue analogue to digitalconverter

modem mo dem

How do you connect? Dialup

Sloooooooooow Broadband

Connect through an ADSL modem. Asymmetric Digital Subscriber Line Fast download speeds and the ability to stay connected

& use the phone. ISDN

lines are digital and they transmit data faster than analogue lines.

ISDN – Integrated Services Digital Network – Communication standard allowing a single wire or optical

fibre to carry voice, digital network services and video. Needs an ISDN Router

The Internet Hierarchy

Sprint

Backbone

PacBell

GXnet

High-speed Backbone Networks (e.g. MCI WorldCom)

BTnet

LINX

PSInetUUnet

Educational Organisation

MFS

Commercial Networks

Network Access Points (NAPs)

Regional Networks

Local ISPs

User Networks

A Brief Trip Around the World

What’s What?

How does your computer know where to send the data?

IP Address Every computer that is connected to the Internet

has to have its own address, just as you need an address to have post delivered to you.

An Internet address is called an IP (Internet Protocol) address, and it is a series of numbers separated by dots like this:

217.27.240.45 Think how difficult it would be to remember the

IP address of the sites you wanted to visit. http://www.corfe-hills.dorset.sch.uk is much

easier!

URL’s

The domain name system links the IP address (217.27.240.45) with the text name (http://www.corfe-hills.dorset.sch.uk ) automatically, which makes it much easier to use.

The text name is what we usually call the web address, but its proper name is a URL or

Uniform Resource Locator

URL’s are usually made up of these parts

WWW, standing for World Wide Web an organization name (.corfe-hills.dorset) a top level domain (.sch) a country (.uk) There are many top level domains, for instance .com, co,

.org (organisation), .sch (school), .ac (university).

When you are deciding whether the information from a web site is reliable, take a look at the URL, as it will give you some idea of where the information is coming from.

OK, now it’s you turn…

Speaking the same language

To allow different computers in to interact, there has to be some agreement about how they communicate.

These standards are called protocols. http is the first part of many web addresses

– it stands for HyperText Transfer Protocol, and states the protocol that the site will use to communicate.

HTML stands for HyperText Mark-up Language, and it is the standard language that web pages are written in.

So, What Software do I need?

Web pages are loaded using a web browser. E.g. Firefox or MS Explorer

A web browser Displays web pages and… Allows you to move back and forward through web pages Allows you to bookmark sites you use regularly or add

them to your favourites list you can set the page your browser first loads up (the home

page) it can store the sites you have recently visited, as history.

Web Pages

A file that is loaded by a web browser. It is written in HTML code, and contains hyperlinks.

click on to a hyperlink, it takes you to another web page, either on the same site or a different one.

Most web sites are several pages linked together which you navigate through using the hyperlinks.

Web Pages – What's in them!

Web pages can contain pictures, videos, animated graphics and sounds as well as text.

File sizes for multimedia can be very large and this can slow down the loading of the web page.

Another Test!

Summary The Internet is a network of networks that connects

governments, people and companies all over the world. The World Wide Web (WWW) was developed to make

browsing (viewing) easier using HTTP (HyperText Transfer Protocol).

HTTP is a set of standards (protocols) that allow web browsers and servers to communicate.

You need an Internet Service Provider (ISP) to connect to the Internet.

Each computer has an IP address (numbers) and each web site has a URL (name) which are linked together.

A web page is a file that is loaded by a web browser. It is written in HTML code, and contains hyperlinks.