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WHAT IS THE INTERNET? A network is made up of two or more connected computers that share information. An internet is a connected group of networks. The Internet is an international connection of computer networks that communicate with each other using the same protocol. Computers can be connected with wires, cables, or via satellite. Hundreds of countries, thousands of organizations, and millions of computers are connected to the Internet. More than 25 million people use the Internet each day! • The Internet is a network of computers spanning the globe. • This communication structure is a system connecting more than fifty million people in countries around the world. • A global Web of computers, the Internet allows individuals to communicate with each other. • Often called the World Wide Web, the Internet provides a quick and easy exchange of information and is recognized as the central tool in this Information Age. Network • Computer Networks (or Networks) are two or more computers connected together to share resources. • Two or more networks connected together form an internet. Protocol • Protocol is a uniform computer standard that allows computers to communicate with one another. • TCP/IP (Transmission Control Protocol/Internet Protocol) is the protocol for computers that are on the Internet. • Every computer on the Internet is part of a network. • It is these connections of computers that make-up the International Network -- or the Internet. HISTORY OF THE INTERNET • The Internet was originally created in the 1960's as a government-sponsored computer network for the United States defense industry. • Over the years, as the Internet became a more powerful and sophisticated way to share information, universities and corporations began using it. • The Internet is made up of five strands or resources: • Gopher • FTP • Telnet • USENET news grous & Electronic Mail • World Wide Web • Most people use the terms Web, World Wide Web, or WWW to refer to the entire Internet, but the Web is only one part of the Internet. • The Web can access ALL other parts of the Internet: Gopher, FTP, USENET, etc. • The Web works by moving information from server computers to client computers using Web browser software (Netscape®, Internet Explorer®, and others). • Some of these Internet strands, like Gopher, FTP, and Telnet were popular in the early years, but were not always easy to use. They were also limited in the kinds of information that they could move from computer to computer. Gopher, FTP, and Telnet were limited to text files or word files. • Files containing graphics, images, pictures, sound, or video could not be shared until the Web was invented. • These days, electronic mail and the Web are the most popular Internet strands. WHAT IS THE WORLD WIDE WEB? • The World Wide Web is the graphical interface strand of the Internet. • It allows text files and multi-media files -- graphics, pictures, moving images, video and movies, and audio/sound -- to be sent and received over the Internet. • The Web also recognizes and leads users to the other four Internet strands (Gopher, FTP, Usenet, and Telnet), making the Internet more seamless and easy to use. • The Web itself does not exist at any one place. • It is truly a web of interconnected documents, files, and computers that together create this thing called the Web. • Like the Internet itself, the Web is constantly changing and evolving as new information is added and expanded. HISTORY OF THE WEB • The Web was invented in 1989 by Tim Berners-Lee and other physicists at the European Particle Physics Laboratory (CERN) in Geneva, Switzerland. They invented the Web because they wanted to use the Internet to share documents that contained both text AND pictures and images (multi-media). • The first Web browser -- the computer software that lets us use the Web -- was released in 1993 by the National Center for Supercomputing Applications (NCSA). It was called Mosaic®. This first Web Browser allowed computer users to use a mouse to move through the Web, and also allowed for graphics and other media to be used in Web documents. • There are dozens of Web browsers on the market today. Most of us use Netscape® or Internet Explorer®. Web Browsers • Web Browsers are software that allow your computer to display Internet resources. • Web browsers are also referred to as ?client programs? because they allow your computer (the client) to read documents or files that come from a server computer. • The first Web browser, Mosaic?, was invented in 1993. • Netscape? and Internet Explorer? are two popular Web browsers in use today. BASIC WEB FUNCTIONS • Any person with Internet access and a Web browser can create a Web site, and any person with Internet access and a Web browser can use that Web site. This allows for individuals, universities, corporations, governments ? anyone and everyone ? to share information on the Web. • The computer that sends the documents or Web pages is called the server. The computer that receives or reads the documents is called the client. Any computer can be a server, and any computer can be a client. BASIC WEB FUNCTIONS • Web sites and pages move from computer to computer something like this: • When you browse the Web, your computer (client) sends out an HTTP request to a server (the computer which houses the requested information). • The server then sends back an HTML -- hypertext markup language Web page. Web documents or "pages" are usually written in HTML or similar Web "languages". • HTTP (hypertext transfer protocol) is the computer protocol that can read HTML documents or pages. URL • A URL -- Uniform Resource Locator (usually pronounced like the name "Earl") is an address on the Web. • Just like every house has a street address, every Web site has a URL. URL: AN ADDRESS ON THE WEB URL FORMATS • URLs follow a particular format or pattern, providing information about the Web site that you are using: URL FORMATS • This is the basic format that a URL follows: protocol://server & domain/directory/file & extension This is the URL for the Yahoo® search engine: http://www.yahoo.com This is the URL for the page that you're reading right now: http://med-libwww.bu.edu/library/tutorial/url.html DOMAIN NAMES • DOMAIN NAMES AND TOP LEVEL DOMAINS (TLD) • Now we know what a URL is, and have seen the parts of a URL, or Web address. Let's talk about Domains. • A domain is the unique name that identifies a Web site. The last (right-hand) part of a domain name is called the Top Level Domain (TLD). • For example, in the domain name www.yahoo.com, the .com is the Top Level Domain (TLD). • Top Level Domain names give us a lot of information about a Web site: who created, sponsors, or produces the information on the site; its intended audience or intended users; and so on. COUNTRY CODE • COUNTRY CODE TOP LEVEL DOMAINS (ccTLD) • Two letter domains are called Country Code Top Level Domains (ccTLD), and correspond to a country, territory, or other geographic location outside of the United States. • For example, if we were looking for news in England, we might go to the BBC site: www.bbc.co.uk • Country Code Top Level Domain (ccTLD) names are two-letter country codes that represent the country or geographic region in which a Web site originates. • The United States also has a ccTLD (.us), but because we are in the U.S., a .us code isn't generally displayed. VOCABULARY REVIEW • Backbone • A high-speed line or group of connections that form a path in a computer network. The term is generally used in reference to smaller networks. Client • A software program that is used to transfer information or documents from a server. Clients can be located nearby or thousands of miles away from the server. A Web Browser is a type of client that allows your computer to read information on the Web. Computer Network • Computer Network (or Network) Two or more computers connected together to share resources. Two or more networks connected together form an internet. Cookie • Information that a server sends to a Web Browser that the browser stores and sends back to the server when additional information is exchanged. Cookies contain information like user preferences, shopping cart contents, registration information, etc. Web browsers can be set-up to accept or not accept Cookies. Cookies can be saved for short or long periods of time. Organizations use Cookies to store information about users that can be used to personalize services or resources, or enhance communication between an organization and a particular user. • Cyberspace A term that many people use to represent the Web, Internet, or the variety of information that is available via computer networks. • Electronic Mail (e-mail or email) Messages that are sent from one person to another, or to a large number of people, via a computer. People exchange their email addresses with one another so that they know where to send the messages. • Domain or Domain Name The unique name that identifies an Internet site. Domain Names have two or more parts, separated by dots. On the left of the dot is the more specific part of the name; on the right of the dot is the more general part of the name: med-libwww.bu.edu yahoo.com mtv.com • FTP (File Transfer Protocol) An Internet resource that was very popular before the Web was invented. FTP is a way of moving files from Internet site to Internet site, by allowing your computer to login to another computer to retrieve information. Like other Internet resources, FTP can only transfer text files, and has been largely replaced in popularity by the Web. • Gopher Gopher was invented around 1993 at the University of Minnesota, just before the Web was invented. Gopher was a very popular method of making text-based information available on the Internet using menus to make information easier to organize and find. As use of the Web grew, Gopher became less popular because it only allowed for the sharing of textbased files, and not multi-media files (graphics, sound, video, etc.) But, thousands of Gopher servers are still on the Internet to this day. • HTML (HyperText Markup Language) The language that is used to write hypertext on the Web. HTML files are viewed using a Web browser. HTTP • (HyperText Transfer Protocol) The protocol (a standard) for sharing hypertext files on the Internet. HTTP requires a client on one end, and a server on the other. HTTP is the most popular protocol for sharing information on the Web. • • ISP (Internet Service Provider) A company or organization that provides Internet access, usually for a monthly fee (America Online®, CompuServe®, and many others). • IP (Internet Protocol address) In order to be on the Internet, every computer must have a unique IP address. An IP address is a combination of numbers that are made up of four parts, separated by commas: 155.32.412.2 An IP number is like a URL or a domain name. But, instead of using words, it uses numbers. While every computer on the Internet must have an IP address, not every computer has to have its own URL or domain name, because URLs and domain names are for computers that are sharing information, NOT receiving it. TCP/IP • TCP/IP (Transmission Control Protocol/Internet Protocol) The protocol (or standard) that defines the Internet. To be "on the Internet," a computer must have the TCP/IP software so that it can communicate with other computers. • USENET news groups Discussion groups that allow hundreds or thousands of people all over the world to share information and comments about a variety of topics. The 10,000+ topics of interest are called newsgroups. USENET computers may or may not be on the Internet. Web Browser Software (like Netscape® or Internet Explorer®) that allows your computer to display Internet resources. Web browsers are also referred to as "client programs" because they allow your computer (the client) to read documents or files that come from a server computer. The first Web browser, Mosaic®, was invented in 1993. Netscape® and Internet Explorer® are two popular Web browsers in use today. • WEB BROWSERS: IMPORTANT INFORMATION BEFORE WE BEGIN