Chapter 5

1. Chapter 5 The internet and the World Wide Web

2. Chapter 5 • Explain how the Internet works. • Describe methods for access the internet. • Define and differentiate between the internet the World Wide Web. • Explain the concept of hypertext. • Contrast Web browsers and Web servers. • Explain how search operators can improve Web search results. • List the most popular internet services and explain what they do .

3. What is the internet • The internet is a global computer network made up of thousands of privately and publicly owned computers and networks that grew and interlinked ,over time ,into one giant network . • Every connected computer can exchange data with any other computer on the network • The internet is referred to as cyberspace • The internet backbone are maintained by network service providers(NSPs)

4. How the Internet Works • Volunteers maintain the Internet networks. • Private and public groups provide the equipment. • Network service providers such as AT&T and Sprint maintain the Internet backbone, the main high-speed routes.

5. INTEROPERABILITY • Interoperability: is the ability to work with the computer even if it is a different brand and model. • Example: when you access the internet using a Mac, you contact a variety of machines that may includes other Macs, Windows PC, Unix machine and even mainframe computers. • The reason is the TCP/IP • TCP/IP supply the standard methods of packaging and transmitting information on the internet .

6. Accessing the internet: going online • Internet service providers(ISPs):companies that provide access to the internet. • Online service : is a for-profit firm that provides a proprietary network offering special services that are available only to subscribers. • ISPs have several roles and responsibilities: • Provide and maintaining a connection to the internet . • Support the Hardware and software needed to service that connection . • ISPs need to protect their site and network from external threats such as viruses, hacker attacks, and other illegal activity

7. Methods to Access the Internet • Dial-up access : • Run over normal telephone lines • While online, your phone is unavailable for calls • Can be external or internal • Speed: 14-56 kbs • Usually the slowest and cheapest connection

8. Methods to Access the Internet • Digital subscriber line(DSL): • Offer faster access speeds than dial-up • Operates over normal telephone lines and can be used simultaneously with the telephone • Average Speed: 1.5 megabits per second. • Cable Access : • provides a high-speed Internet connection using a cable modem • no phone line is needed ,but a cable modem is required.

9. Methods to access the Internet • Satellite access requires a satellite dish in addition to a phone line and modem for an Internet connection. • Satellite for high-speed downloading • Phone line and modem for uploading • Fiber-optic service (FiOS) provides extremely fast Internet access through fiber-optic lines that run directly to users’ homes. No modems are required.

10. The Internet and the Web: What’s the Difference? • The World Wide Web, also known as the Web or WWW: • Contains billions of documents • Is a portion of the Internet • Uses the Internet as a means to transport information • Is a separate entity from the Internet

11. The Internet and the Web: What’s the Difference? • The Internet is the physical connection of millions of network. • The web is one of many applications that run on the top of the Internet architecture.

12. Features of the Internet • A Web page is a document that may include text, graphics, sound, animation, and video. • A Web site is a collection of Web pages. • A Web browser is a program that displays Web pages and linked items. • A Home page is the Web page that displays every time Internet Explorer is started.

13. Features of the Internet • Hyperlinks or links are words and images that bring other documents into view when clicked. • Hypertext uses links to move to additional related information. • Hypertext Markup Language(HTML) is a language that uses a tag system of code to create Web pages. • Extensible Markup Language (XML): alanguage designed to reduce the complexity of HTML

14. Features of the Internet • Plug-insare software programs that browsers use for extra features such as sound and video.

15. Features of the Internet • The most popular Web browsers • Mozilla Firefox • Google Chrome • Internet Explorer • Opera • Safari

16. WEB ADDRESSES • Internet Protocol Address(IP address),a numerical identification and logical address that is assigned to devices participating in a computer network. • Animated banners are used to attract attention and stimulate interest to the Web site. • Animated banners are a series of rotating or changing text and images embedded within the Web page.

17. Exploring Internet Services • Sponsored links are sites that pay to be displayed as results at a search engine site. • Generally commercial sites, so they stand to gain from increasing traffic to their Web site • Frequently placed near the top or on the right side of the search engine results page so they are easily seen and clicked

18. Features of the Internet • The Historyfeature tracks recently visited Web pages and sites. • The History list can be displayed by using the Favorites Center button and then selecting a site that was recently visited. • By default, Internet Explorer tracks sites visited in the last 20 days.

19. Features of the Internet • Web sites and their associated information are stored on computers called Web servers. • Web servers are used to recognize information requests, process the requests, and send the requested documents.

20. Features of the Internet • Every device connected to the Internet, including PCs and servers, is given a unique numerical network identifier called an Internet Protocol (IP) address. • The identification of an Internet resource’s type and location is performed through its Uniform Resource Locator (URL). A URL is a unique web site address.

21. Features of the Internet • The complete URL is made up of the Hypertext Transfer Protocol (HTTP),domain name, path, and resource name.

22. Common Top-level Domain Name

23. Features of the Internet • Downloading is the process of transferring a file or document from one computer to the user’s computer. • Uploading is the process of transferring a file or document from the user’s computer to another computer.

24. Finding Information on the Web • Search engines index databases of Web pages to enable fast information searches.

25. Finding Information on the Web • There are several Web sites with search capabilities called search engines, programs that search for keywords in files and documents or other Web sites found on the Internet.

26. Finding Information on the Web • Specialized search engines index information such as job advertisements, and names and addresses. • Some Web site home pages include portals, which provide organized subject guide links to topics such as the news, local weather, and e-mail.

27. Exploring Internet Services • Pop-ups are distracting windows that display on the screen without being requested. • Many Web users use a Pop-Up Blocker to stop these windows from displaying.

28. Finding Information on the Web • Example of a portal

29. Exploring Internet Services • Electronic mail (e-mail) is a type of application software that makes sending and receiving messages through computer networks possible. • An e-mail attachment is a computer file included withan e-mail message.

30. Exploring Internet Services • An e-mail address, a unique cyberspace address for each individual, consists of a user name, the name of the hosting e-mail service, and the top-level domain. • Unsolicited e-mails received by users, usually from advertisers, are called spam. Do not open spam.

31. Exploring Internet Services • Instant messaging (IM) systems allow immediate, real-time communication with contacts. • Requires additional software • Notifies users when a contact is connected to the Internet • May be susceptible to spimming—spam for instant messaging

32. Exploring Internet Services

33. Exploring Internet Services • Internet relay chat (IRC) is a special type of Internet service that gives users the ability to join chat groups called channels. • Social networking helps people connect. Social networking sites like MySpace provide the ability to create large communities online.

34. Summary • The Internet is a global computer network. • The Internet enables computers connected to it to exchange data. • Public or private Internet service providers supply users with access to the Internet.

35. Summary • The World Wide Web, which is made up of billions of hypertext documents, uses the Internet. • Web browsers display Web documents and give users the ability to use linked documents. • A URL is made up of a protocol, a domain, a path, and a resource name.

36. Summary • Search engines permit users to search the databases of the Web. • Information found on the Web should be critically evaluated for being reputable and accurate.