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 e-mail, 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 e-mail, storing Web pages, or helping send files from one computer to another.

Structure of the Internet

Clients and Protocols Internet clientsClients 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 governmentwanted to find a way to communicate in the event of adisaster or military attack. The military began to work on a systemthat would operate even if some communication connectionswere destroyed. The Defense Advanced Research ProjectsAgency (DARPA) of the U.S. Department of Defense focused oncomputer networking and communications. In 1968, thisresearch led to a network of connected computer centers calledthe 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 theInternet is the ability to share information. Because much of the Internet is available forpublic use, there is a lot of freedom to getinformation from the Internet as well as to add toit. Anyone can make an idea or opinion

accessible to anyone else. Is this good or bad?Is this good or bad?

Pitfalls of the Internet

However, there are pitfalls to this open organization. People canpost whatever point of view or information they want, even if it cansometimes be misleading or false. It is up to the users of theInternet to think critically about the information they find. If you

havea question about anything you find on the Internet, ask an adult youtrust about it.

Because the Internet is not managed and protected by a specificgovernment or agency, each individual has to figure outhow to best use it. The network developed from the ideas of theU.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/InternetProtocol (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 adialup connection between a standard phone line and a modem. These connectionsare called "dialup“ because your computer must connect to the Internet by using atelephone number to contact a server. When the session is over, the connection isbroken. Some Digital Subscriber Lines (DSL) require a special telephone line.Integrated Services Digital Network (ISDN) lines require a special ISDN adapterand modem. As a result, both services cost more than regular phone service.

Cable and Satellite Cable television companies offer Internet access through cablemodems. This access is at speeds much faster than dialup modems. You need anetwork card in your computer, a cable modem, and cable access. Satellite accessIs also very fast for downloading files to your computer, but it requires a phone lineand a modem for sending files to outside users.

Getting Online

After you have access to the Internet, you mustselect a way to get online. Choices includeInternet service providers and online services.

Internet Service Providers An Internet service Provider (ISP) is acompany that provides a link from your computer to the Internet. For afee, an ISP provides its subscribers with software, a password, anaccess phone number, and a username. A username identifies whoyou are when you access the Internet. An ISP does not guide youthrough 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 tothe Internet. Online services are businesses that provide toolsto help you navigate, or move to different parts of, the Internet.

Online services are not the Internet. They provide special softwarethat you load onto your computer. The software makes theconnection to the service, which then guides you through contentand activities. Three popular online services are AmericaOnline (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

network, a set of standards, or protocolsprotocols, is

used to define how things should work.

ProtocolsProtocols 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

123.257.91.7. 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 systemcalled the domain name system using letters as well as numbers wascreated. A domain name identifies one or more IP addresses. If you wantto obtain a domain name, you or your ISP can contact a registeringorganization. It then contacts an organization called InterNIC, which keepsthe master database of domain names.

How do domain names work? Let's say you want your computer toaccess information stored on another computer. Your local ISP's domainname server will contact the domain name server you are calling. Theinformation to identify both computers will be exchanged, and the contactwill be made.Every domain name has an ending, or suffix, that indicates which type oforganization 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 ServicesObjectives

Identify and describe kinds of Internet services.

Summarize how to access information on the Web.

Analyze the usefulness of e-mail 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 e-mail 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

IntranetsIntranets

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 e-mail, 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 e-mail message are not the sameas the protocols for displaying a Web page. Typically, there isdifferent software for each Internet service. You use a Web Browser to view Web pages. The two most popular Web browsersare Safari® and Microsoft Internet Explorer. You use a mailprogram to send and receive e-mail messages. This distinction,however, is beginning to vanish. Hotmail's Outlook WebAccess, for example, uses a Web site to access and send e-mail.

Internet Software

PortalsPortals

Internet portals provide organized subject guides to Internetcontent. They usually offer search engines as well. A searchengine is software that finds and lists information thatmeets a specified search. First, the search engine asks you totype a keyword into a blank field. Then, the search engine willgive you the results of that search. Popular search enginesinclude Yahoo!, Excite, and InfoSeek.

Accessing Information on the World Wide Web

The World Wide Web is a huge collection of hypertext documentscalled Web pages. In a hypertext document, certain words orPictures can serve as hyperlinks. A hyperlink is a link to anotherdocument on the World Wide Web.

Hyperlinks Usually hyperlinks appear underlined, in a differentcolor, or highlighted. Sometimes there are buttons or imagesthat can be clicked. When you move your mouse over a hyperlink,the pointer changes to an icon of a hand. You can click thishyperlink item to be transferred to another document.

Accessing Information on the World Wide WebURLs

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 e-mail, has replaced traditionalmail and telephone services. E-mail is fast and easy. If you organize youre-mail addresses into groups, you can broadcast, or send, a message to agroup in just one step.

E-mail Pros and ConsE-mail Pros and Cons E-mail is not free, and it's not instantaneous.However, you do not pay to send each e-mail, as you would a letter. Thecost of your e-mail service is included in the fee you pay your Internetservice provider or online service provider. In most cases, it takes minutesor more for an e-mail message to reach its destination. But it costs thesame and takes approximately the same amount of time to send amessage to someone in your own city as it does to send a messagehalfway around the world.

Transferring Files

File Transfer Protocol (FTP) lets you transfer files on the Internet. With anFTP client, you can transfer files from an FTP server to your computer inan operation called downloading. In uploading, you transfer files from theclient to the server.

FTP can transfer both text files and binary files. Binary files are programfiles, graphics, pictures, music or video clips, and documents. Once you'vestored a file on an FTP server, you can distribute the URL so that yourfriends can also download the file from the server.

One difference between using an FTP server and e-mail to transfer files isthat with FTP, the file stays on the server until you take it off. With e-mail, afile that has been transferred will be lost once the e-mail message hasbeen deleted. E-mail is considered a more secure method, however,because only the recipient of the e-mail message has access to theattached files.

An e-mail message may travel a long way from

the sender to the receiver.