The Internet Networks This icon indicates the slide contains activities created in Flash. These activities are not editable. For more detailed instructions, see the Getting Started presentation.

What is the Internet? 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 Koji Araki, Japan The Internet Jim’s Skateboards USA, Patel’s Fine Silks, India

The Internet began in the 1980s to allow US universities to share computer resources, and grew so that in the 1990s it became possible for people to use the Internet from home. The World Wide Web (WWW) was developed to make browsing (viewing) easier though HTTP (HyperText Transfer Protocol). HTTP is a set of standards that allow web browsers and servers to communicate.

Uses of the Internet People use the Internet for many reasons: for business, for research and for pleasure. People can communicate in different ways with people all over the world.

How does it work? When you connect to the Internet you connect your computer to an Internet Service Provider (ISP). This is done through telephone or cable services. Computer signals are digital and normal telephone lines are analogue, so you need an analogue to digital converter if you are using an analogue telephone line. This is called a modem (modulator/demodulator).

Broadband connections connect through an ADSL modem Broadband connections connect through an ADSL modem. ADSL – Asymmetric Digital Subscriber Line – is a way of transmitting data at high speeds through existing telephone lines. Broadband allows the user fast download speeds and the ability to stay connected to the service without having to dial up. ISDN lines are digital and they transmit data faster than analogue lines. ISDN – Integrated Services Digital Network – is a set of communications standards allowing a single wire or optical fibre to carry voice, digital network services and video. ISDN is intended to eventually replace the telephone system. To connect to an ISDN line you need an ISDN router.

Using the Internet to access a web site follows the same procedure as shown on slide 7. Try and remember what’s involved next time you are tapping your foot impatiently waiting for a web page to load! The actual connections may be made using microwaves and satellite links, in the same way that telephone calls are connected.

IP address But how does your computer know where to send the data? 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 Can you imagine how difficult it would be if you had to remember the IP address of all the sites you wanted to visit? It’s much easer to remember a web address in words, like: http://www.theboardworks.co.uk.

URLs The domain name system links the IP address (217.27.240.45) with the text name (http://www.theboardworks.co.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.

URLs are usually made up of these parts: www, standing for World Wide Web an organization name (.theboardworks) a top level domain (.co) a country (.uk) There are many top level domains, for instance .com, .org (organization), .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.

Speaking the same language To allow different types of computers in different parts of the world 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.

Software needed In order to connect to the Internet, you will probably need software from your ISP that sets up your connection. Web pages are loaded using a web browser, usually either Microsoft Internet Explorer or Netscape Navigator. A web browser displays the web pages and does other things too: it allows you to move back and forward through web pages it can allow 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 web page is a file that is loaded by a web browser. It is written in HTML code, and contains hyperlinks. When you 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. Screenshot courtesy of http://www.nrich.maths.org.uk/

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. Reproduced with permission of Yahoo! Inc © 2003 by Yahoo! Inc. YAHOO! and the Yahooligans! logo are trademarks of Yahoo! inc.

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.