Internet Basics Lesson 15-1 What Is the Internet? Lesson 15-2 How the Internet Works Lesson 15-3 Comparing Internet Services

Lesson 15-1 What Is the Internet? Objectives Compare and contrast LANs, WANs, and the Internet. Describe how the three main parts of the Internet work together. Explain the advantages and disadvantages of the organization of the Internet. Key Terms: Key Terms: Internet Internet client

The Internet Connects the World No matter where you are on the planet, chances are good that the Internet is there, too. An international communication and information system, the Internet connects millions of computers and people. People use the Internet at school, at work, and at home. At school, students and teachers use the Internet to do research and share information. At work, people use it to send , share files, and communicate with co-workers near and far. At home, people use the Internet to get help with homework, play games, and shop, among other activities. The Internet has changed the way people around the world live and work. It is considered one of the most important and exciting inventions in history.

Organization of the Internet The Internet is a vast network that links together millions of computers around the world. It runs 365 days a year, 24 hours a day.

Structure of the Internet Two or more computers connected to one another are known as a network of computers. Computers linked together in the same building, such as a school, are called a local area network (LAN). Computers or LANs that are linked together over a large area, such as different parts of the country, are called a wide area network (WAN). The Internet is a global WAN, a network of networks. It connects everything from single computers to large networks. The Internet can even connect computers that run different operating systems. This ability to share information with almost any computer makes the Internet a powerful tool for communication.

Structure of the Internet Servers: Servers: The Internet is made up of three important parts: servers, clients, and protocols. Internet servers are the computers that provide services to other computers by way of the Internet. These services include processing , storing Web pages, or helping send files from one computer to another.

Structure of the Internet Clients and Protocols Internet clients Clients and Protocols Internet clients are the computers that request services from a server. When you connect to the Internet, the computer you use is considered a client. Protocols are the special sets of rules that allow clients and servers to connect to one another. Protocols tell computers how to format data and transmit it over a network.

Inventing the Internet In the 1960s, people were working on ideas that later became the Internet. In 1969, the first four major computer centers in the United States were linked. By 1973, the network was international. In 1983, the Internet protocols went online for the first time. Two major groups worked on the development of The Internet: the United States military and university researchers.

Inventing the Internet United States Military In the 1960s, the United States government wanted to find a way to communicate in the event of a disaster or military attack. The military began to work on a system that would operate even if some communication connections were destroyed. The Defense Advanced Research Projects Agency (DARPA) of the U.S. Department of Defense focused on computer networking and communications. In 1968, this research led to a network of connected computer centers called the Advanced Research Projects Agency Network (ARPANET).

Inventing the Internet University Researchers With the military's leadership and funding, DARPA formed computing research centers at universities across the United States. From 1969 through 1987, the number of computers on the network increased from four to more than 10,000. These connections created the networks that became the Internet.

Internet Management Who owns the Internet? The truth is, no specific organization or government does. The Internet is made up of many networks. Each network is managed by an organization, school, company, or government. So, although each part of it is managed, no one is in charge of the entire Internet. This provides both opportunities for growth and problems.

Freedom of the Internet One advantage to the open quality of the Internet is the ability to share information. Because much of the Internet is available for public use, there is a lot of freedom to get information from the Internet as well as to add to it. Anyone can make an idea or opinion accessible to anyone else. Is this good or bad?

Pitfalls of the Internet However, there are pitfalls to this open organization. People can post whatever point of view or information they want, even if it can sometimes be misleading or false. It is up to the users of the Internet to think critically about the information they find. If you have a question about anything you find on the Internet, ask an adult you trust about it. Because the Internet is not managed and protected by a specific government or agency, each individual has to figure out how to best use it. The network developed from the ideas of the U.S. military and university researchers has now become a global, open system of communication and information.

Lesson 15-2 How the Internet Works Objectives Identify ways to connect to the Internet. Compare and contrast Internet Service Providers and online services. Summarize the need for protocols. Distinguish between Internet Protocol addresses and domain names. Key Terms: Key Terms: Internet service provider (ISP) username online service navigate Transmission Control Protocol/Internet Protocol (TCP/IP) Internet Protocol (IP) address domain name system

Accessing the Internet There are different ways to connect to the Internet. The reasons for various options are availability, location, speed, and price. 1. Dial up 2. DSL 3. Cable 4. Satellite

Accessing the Internet Dialup, ISDN, and DSL Access The least expensive way to get online is to use a dialup connection between a standard phone line and a modem. These connections are called "dialup“ because your computer must connect to the Internet by using a telephone number to contact a server. When the session is over, the connection is broken. Some Digital Subscriber Lines (DSL) require a special telephone line. Integrated Services Digital Network (ISDN) lines require a special ISDN adapter and modem. As a result, both services cost more than regular phone service. Cable and Satellite Cable television companies offer Internet access through cable modems. This access is at speeds much faster than dialup modems. You need a network card in your computer, a cable modem, and cable access. Satellite access Is also very fast for downloading files to your computer, but it requires a phone line and a modem for sending files to outside users.

Getting Online After you have access to the Internet, you must select a way to get online. Choices include Internet service providers and online services. Internet Service Providers An Internet service Provider (ISP) is a company that provides a link from your computer to the Internet. For a fee, an ISP provides its subscribers with software, a password, an access phone number, and a username. A username identifies who you are when you access the Internet. An ISP does not guide you through the Internet—it only provides an easy-to-use connection to it. You can use either a local ISP or a national TSP.

Getting Online Online Services: An online service connects your computer to the Internet. Online services are businesses that provide tools to help you navigate, or move to different parts of, the Internet. Online services are not the Internet. They provide special software that you load onto your computer. The software makes the connection to the service, which then guides you through content and activities. Three popular online services are America Online (AOL), Microsoft Network® (MSN), and Yahoo®.

Protocols The Internet provides a way to link a single computer or smaller networks to a larger network. To transfer data from network to protocols network, a set of standards, or protocols, is used to define how things should work. Protocols Protocols determine how networked computers communicate, format data, and transmit data.

Protocols Internet Protocols Internet protocols are referred to as Transmission Control Protocol/Internet Protocol or TCP/IP. TCP defines how one Internet-connected computer contacts another and exchanges information. IP defines the Internet addresses.

IP Addresses Each computer that connects to the Internet has to be uniquely identified. To do this, every computer is assigned a four-part number separated by periods called the Internet Protocol (IP) address. For example, the IP address for your computer might be The administrator of the network to which your computer connects assigns your IP address.

Domain Names IP addresses can be difficult to remember, so a simpler naming system called the domain name system using letters as well as numbers was created. A domain name identifies one or more IP addresses. If you want to obtain a domain name, you or your ISP can contact a registering organization. It then contacts an organization called InterNIC, which keeps the master database of domain names. How do domain names work? Let's say you want your computer to access information stored on another computer. Your local ISP's domain name server will contact the domain name server you are calling. The information to identify both computers will be exchanged, and the contact will be made. Every domain name has an ending, or suffix, that indicates which type of organization registered the name. The following table lists these suffixes— called top-level domains—and the types of organizations they represent.

Top-Level Domain

Lesson 15-3 Comparing Internet Services Objectives Identify and describe kinds of Internet services. Summarize how to access information on the Web. Analyze the usefulness of in daily living.. Key Terms: Key Terms: Web browser portal search engine hypertext hyperlink uniform resource locator (URL) download upload

Internet Services When you send an message to a friend, you use one kind of Internet service. Browsing the World Wide Web is done through another type of service. Different Internet services are used for accessing the World Wide Web, sending and receiving electronic mail, and conducting file transfers.

Internet Services Intranets The Internet uses protocols that define how the client software and server software communicate. In the same way, some organizations have their own networks of services, called intranets, which are private. Employees can use , the Web, and other Internet technologies with their company's intranet. Intranets, however, are used within a company and are not open to the public.

Internet Software The protocols for delivering an message are not the same as the protocols for displaying a Web page. Typically, there is different software for each Internet service. You use a Web Browser to view Web pages. The two most popular Web browsers are Safari® and Microsoft Internet Explorer. You use a mail program to send and receive messages. This distinction, however, is beginning to vanish. Hotmail's Outlook Web Access, for example, uses a Web site to access and send .

Internet Software Portals Internet portals provide organized subject guides to Internet content. They usually offer search engines as well. A search engine is software that finds and lists information that meets a specified search. First, the search engine asks you to type a keyword into a blank field. Then, the search engine will give you the results of that search. Popular search engines include Yahoo!, Excite, and InfoSeek.

Accessing Information on the World Wide Web The World Wide Web is a huge collection of hypertext documents called Web pages. In a hypertext document, certain words or Pictures can serve as hyperlinks. A hyperlink is a link to another document on the World Wide Web. Hyperlinks Usually hyperlinks appear underlined, in a different color, or highlighted. Sometimes there are buttons or images that can be clicked. When you move your mouse over a hyperlink, the pointer changes to an icon of a hand. You can click this hyperlink item to be transferred to another document.

Accessing Information on the World Wide Web URLs When you click a hyperlink, the Web browser retrieves and displays the document connected to that hyperlink. How does this work? Every document has a unique address, called a uniform resource locator (URL), which tells exactly where the document is located on the Internet. A hyperlink instructs the browser to go to the URL for that document.

Electronic Mail For many Internet users, electronic mail, or , has replaced traditional mail and telephone services. is fast and easy. If you organize your addresses into groups, you can broadcast, or send, a message to a group in just one step. Pros and Cons Pros and Cons is not free, and it's not instantaneous. However, you do not pay to send each , as you would a letter. The cost of your service is included in the fee you pay your Internet service provider or online service provider. In most cases, it takes minutes or more for an message to reach its destination. But it costs the same and takes approximately the same amount of time to send a message to someone in your own city as it does to send a message halfway around the world.

Transferring Files File Transfer Protocol (FTP) lets you transfer files on the Internet. With an FTP client, you can transfer files from an FTP server to your computer in an operation called downloading. In uploading, you transfer files from the client to the server. FTP can transfer both text files and binary files. Binary files are program files, graphics, pictures, music or video clips, and documents. Once you've stored a file on an FTP server, you can distribute the URL so that your friends can also download the file from the server. One difference between using an FTP server and to transfer files is that with FTP, the file stays on the server until you take it off. With , a file that has been transferred will be lost once the message has been deleted. is considered a more secure method, however, because only the recipient of the message has access to the attached files.

An message may travel a long way from the sender to the receiver.