Section 8a Internet Basics

This lesson includes the following sections: How the Internet Works Major Features of the Internet Online Services Internet Features in Application Programs

How the Internet Works TCP/IP: The Universal Language of the Internet Routing Traffic Across the Internet Addressing Schemes Domains and Subdomains

How the Internet Works - TCP/IP Every computer and network on the Internet uses the same protocols (rules and procedures) to control timing and data format. The protocol used by the Internet is the Transmission Control Protocol/Internet Protocol, or TCP/IP. No matter what type of computer system you connect to the Internet, if it uses TCP/IP, it can exchange data with any other type of computer.

How the Internet Works - Routing Traffic Across the Internet Most computers don't connect directly to the Internet. Instead, they connect to a smaller network that is connected to the Internet backbone. The Internet includes thousands of host computers (servers), which provide data and services as requested by client systems. When you use the Internet, your PC (a client) requests data from a host system. The request and data are broken into packets and travel across multiple networks before being reassembled at their destination.

How the Internet Works - Routing Traffic Across the Internet (Cont.) Suppose that you request data from a server Your request must be broken into packets The packets are routed through your local network, and possibly through one or more subsequent networks, to the internet backbone After leaving the backbone, the packets are then routed through one or more networks until they reach the appropriate server and are reassembled into the complete request Once the destination server receives your request, it begins sending you the requested data.

How the Internet Works - Addressing Schemes In order to communicate across the Internet, a computer must have a unique address. Every computer on the Internet has a unique numeric identifier, called an Internet Protocol (IP) address. Each IP address has four parts – each part a number between 0 and 255. An IP address might look like this: 205.46.117.104.

How the Internet Works - Domains and Subdomains In addition to an IP address, most Internet hosts or servers have a Domain Name System (DNS) address, which uses words. A domain name identifies the type of institution that owns the computer. An Internet server owned by IBM might have the domain name ibm.com. Some enterprises have multiple servers, and identify them with subdomains, such as products.ibm.com. Outside the United States, domains usually identify the country in which the system is located, such as .ca (Canada), .fr (France)

網際網路領域

新的頂層領域名稱

正在考慮中頂層領域名稱

Major Features of the Internet The World Wide Web E-Mail News Telnet File Transfer Protocol (FTP) Internet Relay Chat (IRC)

Major Features of the Internet - The World Wide Web Internet Service Provider: Hinet, Seednet… World Wide Web (the Web or WWW) was created in 1989 in Switzerland as a method to create hypertext document. A hypertext document is a specially encoded file that uses the hypertext markup language (HTML). This language allow users to embed hypertext links (hyperlinks or links) in the document. A collection of related Web pages is called Web site, which are housed on Web servers.

Major Features of the Internet - Web Browsers and HTML Tags Copying a page onto a server is called posting (publishing or uploading) the page. The Web is not popular until 1993, when Mosaic, a point-and-click Web browser (or browser), was developed. To format a document, a designer places HTML tags (<>) throughout the document. <H1> This is a test </H1> A slash (/) indicates an ending tag

Major Features of the Internet - HTTP and URLs The transfer of Web pages is based on Hypertext transfer protocol (HTTP). Every Web page has an address, a Uniform Resource Locator (URL). type://address/path/ http://www.ncue.edu.tw/cc2002 ftp://sunsite.unc.edu/pub/micro/pc-stuff

This address is for an Internet server that uses The hypertext transfer protocol. This site belongs to a company named Glencoe. This site is on the part of the Internet known as the World Wide Web. To find the specific Web pages that accompany this book, your browser follows the URL’s path to a folder named “norton,” then to a subfolder named “online.”

每一個網頁有它自己的唯一URL，它會指引您的瀏覽器到文件的所在位置。

Major Features of the Internet - Helper Applications and Search Engine Helper application (or plug-in applications) Streaming audio and streaming video Use buffer-and-play technique to play a large file without waiting for the entire file to download Virtual Reality Modeling Language (VRML) Search Engine Use powerful data-searching techniques to discover the type of content available on the Web.

Major Features of the Internet - E-Mail Electronic mail (e-mail) is the most popular reason people use the Internet. To create, send, and receive e-mail messages, you need an e-mail program and an account on an Internet mail server with a domain name. To use e-mail, a user must have an e-mail address, which you create by adding your user name to the e-mail server's domain name, as in jsmith@aol.com.

Major Features of the Internet - News One Internet-based service, called news, includes tens of thousands of newsgroups. Each newsgroup hosts discussions on a specific topic. A newsgroup's name indicates its users' special topic of interest, such as alt.food.cake. To participate in a newsgroup, you need a newsreader program that lets you read articles that have been posted on a news server. You can post articles for others to read and respond to. Thread of articles: a list of related articles

Major Features of the Internet - Telnet Telnet is a specialized service that lets you use one computer to access the contents of another computer – a Telnet host. A Telnet program creates a "window" into the host so you can access files, issue commands, and exchange data.

Major Features of the Internet - File Transfer Protocol (FTP) File transfer protocol (FTP) is the Internet tool used to copy files from one computer to another. Using a special FTP program or a Web browser, you can log into an FTP host computer over the Internet and copy files onto your computer. FTP is handy for finding and copying software files, articles, and other types of data. Universities and software companies use FTP servers to provide visitors with access to data. Archie: the searchable index of FTP files

Major Features of the Internet – Internet Relay Chat (IRC) Internet Relay Chat (IRC) is a service that allows users to communicate in real time by typing text in a special window. Like news, there are hundreds of IRC "channels," each devoted to a subject or user group. You can use a special IRC program to participate in chatroom discussions, but many chatrooms are set up in Web sites, enabling visitors to chat directly in their browser window.

Major Features of the Internet – Internet Relay Chat (IRC) Another twist on chat is instant messenger software MSN Messenger Serivce, ICQ http://www.geocities.com/Tokyo/4097/icq/ http://messenger.msn.com.hk/Default.asp?MSID=2717b66146274db48de0f0d27d5b7a13

Services Related to the Internet Online Services. Peer-to-Peer Services

Online Services An online service is a company that provides access to e-mail, discussion groups, databases on various subjects, and the Internet. America Online, CompuServe, and Prodigy are examples of popular online services.

Peer-to-Peer Services Peer-to-Peer (P2P) services are distributed networks that do not require a central server to manage the files. Allow an individual’s computer to communicate directly with another individual’s computer and even access files on that computer.

立即傳訊軟體讓使用者在網際網路上以點對點(peer-to-peer)的連接方式進行聊天

Internet-Related Features in Application Programs Popular application programs, such as word processors and spreadsheets, feature Internet-related capabilities. Using these special features, you may be able to create content for publication on the Internet or view content directly from the Internet.

Internet-Related Features in Application Programs Retrieving Content: Creating Content: three methods exist Save as HTML Command: e.g. Save As HTML in Word Web Templates: predesigned web page Wizards: A wizard appears as a series of dialog boxes that ask questions and prompt you to make choices.

Sectiion 8a review Name the two organizations that created the network now called the Internet. Explain the importance of TCP/IP to the Internet. Describe the basic structure of the Internet. List the major services the Internet provides to its users. Identify two key Internet-related features found in many software applications.