The Internet is far more than just the World Wide Web. The Web was created in 1989 and became popular in the 1990s. In contrast, the Internet is a product of the 1960s and the Cold War era. This lesson builds the foundation for your understanding of the Internet, the various ways in which you can retrieve and contribute information, and the naming and addressing conventions you must understand to use the Web or any other aspect of the Internet.

History of the Internet

The Internet is a vast network of networks that electronically connects millions of people worldwide. It was formed in 1968, when the Department of Defense created the Advanced Research Projects Agency (ARPA), also called the Defense Advanced Research Projects Agency (DARPA). Its first global computer network, Advanced Research Projects Agency Network (ARPANET), allowed government and researchers to interact, and to work from any location on the network. It was specifically designed to function under extreme conditions, such as bombing attacks, severe weather, widespread power failures, and other major disruptions. ARPANET's design featured multiple hosts and multiple connections among those hosts, which greatly reduced the chances of total network failure. There was no central hub, which would have created a point of vulnerability; rather, control was spread throughout the network. This decentralization resulted in a robust and reliable network that would continue to function even if many of the hosts were incapacitated.

In the 1980s, the Department of Defense assigned the ARPA project to the National Science Foundation (NSF). The NSF increased the number of supercomputers to five and added access to more networks, expanding the range of sites for businesses, universities, and government and military installations. The NSF network (NSFnet), plus thousands of others, make up what has become the largest network of networks: the Internet.

In the years that followed, more private companies joined the Internet. The hardware and communications links required to connect to the Internet were funded by a combination of private and government money. Despite continued predictions by some users that increased business involvement would severely disable the Internet, growth has continued at an astounding rate. Businesspeople everywhere see that connecting to the Internet via the Web is a good value, and they are willing to fund its phenomenal growth by paying for better, faster access.

To expand upon the history of the Internet, a good resource is the most recent version of the book by Hafner, Katie, and Lyon, Matthew (Contributor). Where Wizards Stay Up Late: The Origins of the Internet. The book concentrates on the people, universities and technologies that helped create the Internet.

The World Wide Web

Created in 1989 by the European Laboratory for Particle Physics, the World Wide consortium (W3C) An international Web presents information through multimedia formats. graphics, sound, industry consortium animation, and video. The World Wide Web Consortium (W3C), headed by the founded in 1994 to Laboratory for Computer Science at the Massachusetts Institute of Technology, develop common standards for the promotes standards and encourages interoperability among Web products. Funded World Wide Web. by industry members, W3C also works with the global community to produce specifications and reference software. Its products are free to all.

The Web employs several tools to provide a visual layout: hypertext links, browser software, and code structure. These tools will be discussed throughout this module.

The Web resembles an electronic library, and therefore each location or Web site is like a book. Each book has a contents page as its doorway to the other pages in the book, as well as to all the other books in the electronic library. These books are created using the Hypertext Markup Language (HTML). These materials, along with interactive objects such as Java, JavaScript, VBScript, and applets, can be viewed in the source code.

How the Internet Works

The Internet is decentralized; that is, when you are connected to one Internet workstation, you are connected to the entire Internet.

Internet communication is made possible by the Transmission Control Protocol/Internet Protocol(TCP/IP) software on your computer. This software sends information to the computer with which you are connected, which then passes it on to other computers until it reaches the destination. Your software does not have a map of the entire Internet, and does not know the route your transmission will take. You may recall that numerous possible routes exist between your workstation and any other; in essence, all paths through the Internet lead to your destination.

TCP/IP does a lot of work to make certain your information or e‑mail message is transferred quickly and reliably. It breaks your small transmission into packets and sends each packet separately. If a packet is lost, the entire transmission does not need to be repeated; the TCP/IP process simply resends the missing packet. If one of the connections between two computers is not working, there is no need for all the computers on the Internet to be informed; the nearby computers simply stop using that route until the connection is repaired. The Internet protocol recognizes damage and routes around it. The routing flexibility of TCP/IP software assures an accurate and steady flow of information, regardless of any one user's connection.

Businesses with solid Internet connections and good providers thrive in this environment. If a connection is lost, a site need only arrange a connection with any other Internet site.

Another assurance provided by the routing flexibility of the TCP/IP software is that censorship is almost impossible. An Internet site administrator may decide not to receive information from or transmit to a particular site, but the information will continue to be accessible to other Internet users as long as a path exists around the censoring site. The Internet interprets censorship as a damaged connection, and routes around it.

IP addresses

As you can imagine, the original creators of the Internet recognized the need for a standard for the flexible addressing system powerful enough to accommodate the enormous number of current and future users.

They decided that every site on the Internet would be given an Internet Protocol (IP) address, used by TCP/IP to address packets. Most Internet software works with domain names, a concept that will be discussed later in this lesson. Internet addresses are also referred to as dotted quads, because the series of numbers is broken into four segments. A sample IP address is 204.115.34.10.

Each of the four numbers in an IP address is between 0 and 255. Some number values are reserved, but there are roughly 256 x 256 x 256 x 256 different IP numbers, separated by dots. Also referred addresses possible‑approximately 4 billion.

Nevertheless, not enough IP addresses are available for everyone who wants to join the Internet community. Since commercial enterprises have become involved, IP address demand has quadrupled. Many companies reserve entire blocks of IP addresses to simplify connecting their Local Area Network (LAN) to the Internet. For example, a medium‑sized business with a 10‑station LAN might reserve a class C Internet address‑a block of 256 IP addresses that all have the same first three components in their dotted quad.

Although corporations have contributed to the increased growth and success of the Internet, they have also caused a shortage of available IP addresses. Work is already under way to enhance TCP/IP software to deal with the phenomenal growth the Internet is experiencing, and to meet the increasing demands for representative IP addresses.

Clients and Servers on the Internet

Most businesses operate client/server systems. In a client/server environment, programs run on many desktops at once and interact with a server program that runs on a single central computer. A common misconception is that client/server systems are a relatively recent innovation. In fact, the Internet is a client/server system that has been in use since 1968. This strong embrace of the Internet by businesses needing to transmit large files, or many small files, is filling the limited Internet bandwidth quickly. Client programs conserve bandwidth by processing information locally before sending it out to the network.

E‑mail clients and servers

Internet e‑mail is contained within an e‑mail client program. The user can edit a message repeatedly before sending it, and can work offline until ready to access the Internet connection. Many e‑mail client programs support address books, cut-and‑paste functions, insertion of files and graphics, and other user‑friendly features. When the message is finished, the user presses Send or indicates in some other way that the message is ready to be sent.

The e‑mail client computer can then connect to the Internet, send the message to an e‑mail server, and close the connection. The server does not have to perform complex error checking, because the client formatted the message in the Internet e‑mail standard. The recipient can then connect with his or her e‑mail server to retrieve the message.

Although the Internet was developed with client/server technology to reduce bandwidth use, a surprising new outcome developed. Once the rules describing the formats shared by client and server programs were formalized, it became possible for innovators to write slightly different client programs. These programs could speak to the same servers as before, but they had more features or they could run on different operating systems. This development was the beginning of the modern Internet, with its huge array of client programs that offer accessibility to a wide variety of operating systems.

The Internet was initially designed to operate on the UNIX platform, limiting its use almost exclusively to universities and the government. Subsequently, the UNIX client/server architecture opened the network to any operating system (Windows 95/98/2000/NT, Novell NetWare, Apple Macintosh), and to any programmer who wanted to write a client/server program.

Connecting to the Internet

To support an Internet client, you must have six elements:

• Computer, ‑PC, WebTV, Internet phone, or handheld device.
• Operating system‑Windows 95/98/2000, Windows NT, UNIX.
• TCP/IP protocol stack used to communicate with the Internet.
• Client software‑Web browser, e‑mail and news client programs.
• Internet connection‑dial‑up or direct connection to an Internet Service Provider (ISP).
• Internet addresses‑Web addresses (e.g., www.ciwcertified.com), e‑mail addresses.

Although this may seem like an intimidating list, the first three items are generally acquired when you buy a computer. When you or your employer arranges to connect your computer to the Internet, you must install client software, implement a connection method, and identify the addresses of servers you can use. Within the business environment, the corporate Information Technology (IT) department may set up your system for you.

If you are connecting your computer yourself, client software is available from ISPs. Call an ISP of your choice (discussed later in this lesson), and it will often mail you a CD‑ROM that contains customized software, as well as Web browser, e‑mail and news software. ISP personnel will also instruct you how to connect to the Internet, and provide you with Internet addresses to configure your client software.

Although several Internet connection options exist, two principal ways exist to connect to the Internet. Each method requires the services of an Internet Service Provider (ISP). An ISP provides Internet access for both corporations and individual users.

• Dial‑up connection‑Dial‑up connections access the Internet on a per‑use basis, and use a modem. Users gain Internet access when their computer contacts an ISP, and the ISP transfers them to the Internet. When users finish, they disconnect from the ISP. The speed with which you can access the Internet is determined primarily by the speed capability of your modem. To gain faster dial‑up connections, you can install an integrated services digital network (ISDN) line, which is a digital phone line.

• Direct connection-Direct connections provide continuous, "always on," access to the Internet. This method is convenient and fast, because permanent network connections are generally capable of handling high bandwidth. If your employer has connected your LAN to the Internet or you have a cable or Digital Subscriber Line (DSL) modem installed, the computer on your desk may have a direct connection. Direct connections will gain in popularity as newer technologies become more widely available, such as cable modems and DSL.

The term "modem" is widely used, but does not always assume an analog‑to‑digital translation, For instance, cable, D$L, and ISDN modems are used on all digital networks‑no translation to analog is required. The term modem has been used to describe any device that adapts a computer to a phone line or cable TV network, whether it is digital or analog. To differentiate, the term "analog modem" is often used to indicate a traditional modem.

Dial‑up connection

When you use a phone line and modem to connect to the Internet, you are most likely using a dial-up connection. Most dial‑up connections use either Serial Line Internet Protocol (SLIP) or Point‑to‑Point Protocol (PPP) connections. Typically, the modem will dial the ISP and connect using PPP. SLIP is an older protocol that has been widely replaced by PPP. When you have made the

connection with your ISP, your computer can access the ISP's services, which usually includes Internet access.

Many dial‑up accounts use online services, such as America Online (AOL) and the Microsoft Network (MSN), that offer businesses features in addition to regular Internet access. Some will filter the Internet to make it safer or more relevant to a business or younger audiences. Features may include access to fee‑based search services that are useful to the business community. Most online services charge a flat monthly rate.

Other dial‑up accounts include ISPs such as Earthlink, Apex Global Information Services, and AT&T. These services do not provide content or proprietary software. They only provide a connection to the Internet. Like online services, you usually purchase access at a flat monthly rate. However, the cost for basic­ service ISPs is dropping considerably. Some ISPs offer Internet connectivity for

free.

A few older ISPs provide a "shell account," which is a command line interface. It requires users to enter commands to access and navigate the Internet. Today, most users use the point‑and‑click method through a browser's graphical user interface (GUI).

Table 1‑1 displays common modem speeds for dial‑up connections.

Connectivity speeds are measured in bits per second. A thousand bits per second is read "kilobits per second (Kbps). " A million bits per second is read "megabits per second (Mbps)."

Table 1‑1: Common speeds for dial‑up connections.

As previously mentioned, ISDN requires digital phone lines. Therefore, you must contact your local phone company and have it install ISDN lines into your home or business. An ISDN modem, which is technically a "terminal adapter," is attached to a computer that transfers data over the digital phone lines. The ISDN line consists of several channels, which are used for transmitting data.

The most inexpensive method for accessing the Internet is to use your existing phone lines, purchase an analog modem (such as a 56‑Kbps modem), and locate an ISP that serves your area.

WebTV also utilizes dial‑up connections to access the Internet. Even though a WebTV box sits on your TV and uses your TV as the monitor, it usually uses an analog modem and a phone line to connect to the Internet.

Direct connection

A direct, or "always on," connection can be accomplished many ways. This section will discuss several direct connections used for Internet access:

·        LAN connection.

·        Cable TV.

·        Digital Subscriber Line (DSL).

LAN connection

You can connect a LAN to the Internet through a special hardware component called a router. (Most corporate connections also involve firewalls, which will be discussed later.) The LAN router is connected to another router at the ISP by a high‑speed line. The line between the corporation's network and the ISP is paid for monthly, and can cost $250 or less per month for a small‑business connection to $40,000 or more per month for a large corporation, depending on the speed and the amount of traffic.

Cable TV

Network Interface Card (NIC) A hardware device installed in a computer that serves as the interface between a computer and a network. When using a cable modem, an additional cable connects a computer's NIC to the modem.

You can also create a direct connection to the Internet by using a cable modem, provided your cable TV company has prepared your location for the technology. Cable modems access the Internet through cable TV lines. If you already receive cable TV, then your cable company may also offer cable Internet access. It requires purchasing or leasing a cable modem, which connects your computer to the cable TV line. You may also require a Network Interface Card (NIC) to attach your computer to the cable modem.

Another option is "Cable Internet." Cable Internet is a technology that connects your TV to the Internet using an enhanced set‑top cable box. The cable box accesses the Internet through the cable TV line.

DSL

Another direct‑connection method is DSL, which uses digital phone lines and a DSL modem. You must check and see if your local phone company supports DSL. If so, its employees may have to visit your location for installation, depending on the type of DSL offered. You will also need a DSL modem and possibly a NIC to attach your computer to the DSL modem. DSL may eventually replace ISDN, and DSL competes directly with cable modems.

 Many bandwidth connection speeds are associated with direct connections. Several are outlined in Table 1‑2.

Table 1‑2: Common types of direct connections

Cable and DSL modems are usually limited to 10 Mbps because of the NIC. Only the ISPs are capable of achieving the maximum rates. Also, many cable modems must share the cable network with other users in their neighborhood. The speed of the cable modem depends on how many users are online at a given time. Likewise, the speed of a DSL modem depends on the distance between the DSL modem and the phone company's main distribution frame. Speeds below 512 Kbps are common on both cable and DSL modems

Internet Protocols

Protocols are the rules that describe how clients and servers communicate across a network. The protocols used currently (see Appendix A) were developed in the early days of the Internet, and are similar in concept to the rules of diplomatic interaction that dictate who speaks first, who bows to whom, and so forth. You are about to examine these early protocols, which include File Transfer Protocol (FTP), electronic mail (e‑mail), Telnet, News and Gopher. Most recently, the World Wide Web and Hypertext Transfer Protocol (HTTP) joined the ranks. You will get a chance to use each of these protocols in this course.

Hypertext Transfer Protocol (HTTP)

HTTP is used to transfer Web pages from a Web server to a Web client, which is commonly called a browser. Millions of public Web servers worldwide are hosting Web pages at any time.

File Transfer Protocol (FTP)

FTP was originally developed to allow researchers to give one another access to programs and large data files. The early users protected most of their file access with simple user IDs and passwords, but many set aside small parts of FTP sites for anonymous, or general, access. To obtain access to files through an anonymous FTP server, you use the general user ID "anonymous," and provide your e‑mail address as the password. Anonymous FTP site access is so popular that many FTP clients connect you automatically. FTP servers are scattered throughout the Internet, and are generally accessible to anyone. FTP servers are no longer used exclusively by universities; businesses have quickly discovered uses for these efficient information, access, and distribution points.

Electronic mail (e‑mail)

E‑mail actually involves two mail servers: an outgoing and an incoming. You send e‑mail to others with an outgoing mail server using the Simple Mail Transfer Protocol (SMTP). You receive e‑mail from an incoming mail server using the Post Office Protocol (POP) or the Internet Messaging Access Protocol (IMAP).

You can use separate servers for outgoing and incoming e‑mail, or a single server for both tasks. Although you can send e‑mail to any user on the Internet, you need an account and password to receive it. The original Internet developers thought that e‑mail would be a minor tool, and were amazed that it became the primary source of Internet traffic from the beginning.

Telnet

The Telnet protocol is used with shell (text‑only) accounts. It allows a user at one site to connect with a remote system at another site as if the user's terminal were connected directly. In the past, it was widely used by universities and researchers. Some public Telnet servers such as Archie, which will be discussed later, provide additional services.

Newsgroups

Usenet (USEr NETwork) was developed in 1979 as an alternative to the Internet. As the Internet became increasingly popular, it absorbed Usenet, which is now often referred to as "Internet Newsgroups." The Network News Transfer Protocol (NNTP) was developed in 1985 and allows sites on the Internet to exchange Usenet news articles, which are organized into topics such as "programming in C++" or "international trade issues." Other newsgroups discuss topics far less relevant to business. To use newsgroups, you must have access to a news server, which authorizes you to read and post news.

Gopher

Gopher, developed at the University of Minnesota, is very similar in concept and practice to today's Web: users follow links from site to site in search of information. It was one of the first tools developed to pull the Internet together so users could access the entire Internet rather than just one site. Unlike on the World Wide Web, administrators and librarians‑rather than users‑created the links, so Gopher resources tend to be phone books and library catalogs, as opposed to the more eclectic mix found on the Web. Most Gopher servers have been replaced with Web servers.

Gopher searches for and retrieves documents using a browser or a Gopher viewer, such as WS Gopher. Interactive forms enable keyword searches of Gopher space using Veronica (Very Easy Rodent‑Oriented Netwide Index to Computer Archives) and other search engines. Gopher allows you to browse for information (usually text‑based) without having to know exactly where the information is located. It allows you to tunnel across the Internet to access library catalogs and different types of files.

Domain Name System (DNS)

DNS is another important Internet protocol. It has been given its own section because understanding its function facilitates using the other Internet protocols. For instance, when you use your Web browser to retrieve a Web page from a server or tell an e‑mail client how to find your e‑mail server, you must first identify the server. As previously mentioned, one way to identify the server is to provide the IP address, which is the dotted quad. However, because they are easier to remember, most users‑professional and casual‑prefer to use domain names.

A Domain Name System (DNS) translates the dotted quad IP addresses into easily recognizable server names. For example, the CIW program has a Web server at www.ciwcertified.com, which can also be reached with 207.19.199.245. Both the name and the dotted quad refer to the same Web server, but the former is much easier to remember. Without DNS, end users would be forced to enter long numerical strings every time access was needed to any part of the Internet.

One way to remember domain names is to understand their structure, which can tell you a great deal about the site. Businesses choose their domain names very carefully, so other businesses and users will be able to recall them for future reference.

Each domain name is unique. Once a name within a domain category such as .corn is assigned, no other organization or individual may use that name within that category. For example, no other Web server may use prosofttraining.com. However, ciwcertified.org is still available, as is ciwcerffied.net.

Learning to read domain names

A domain name consists of letters and numbers separated by dots and includes two or more words. The last word in a domain name will be a two‑ or three‑letter code, as we will discuss later. The other components are limited to 22 characters total. Many domain names feature abbreviations to make them easier to type; these typically date from the 1980s and earlier, when most names had to be typed repeatedly.

With the advent of features such as copy and paste, address lists, and favorites lists, names selected during the 1990s tend to be longer and easier to remember. In fact, some companies that have been on the Internet for decades are changing their domain names for this reason. Consider the example of SoftQuad, a Canadian company that sells HoTMetaL, an HTML editor for building Web pages, and other Internet development software. SoftQuad was sq.com when it first joined the Internet; a Web server at www.sq.com serves Web pages about this company. Its short domain name was convenient for customers and employees to type. Recently, SoftQuad added the name softquad.com as a synonym for sq.com, and www.softquad.com as a synonym for www.sq.comtwo new names for the same domain. So many businesses have domain names such as www.companyname.com that some people believe all companies must have names in this format. This belief is not entirely accurate.Domain name syntax

A domain name, read right to left, goes from general divisions to specific companies, to departments within the company and even to individual computers (such as a Web server or an e‑mail server). For example, www.ciwcertified.com is:

·         com: a commercial site.

·         ciwcertified: the company that owns the program.

·         www: the name of the Web server at that company, also called the Web site host.

Thus, this domain name identifies a specific Web server at the company that owns the CIW certification program.

Some companies further subdivide their domain names into departments or individual workstations. For example, if a company wants to divide the domain companyname.com by department, it might choose to use research.companyname.com and sales.companyname.com. Or it might use dallas.companyname.com and newyork.companyname.com, dividing by geography. For example, www.research.microsoft.com is:

·         com: a commercial site.

·         microsoft: Microsoft Corporation.

·         research: Research division of Microsoft.

·         www: Web site host for the Research division.

Thus, this domain name identifies a specific Web server at Microsoft.

Some sites name each computer on the LAN and give them all unique domain names. You may not understand why a workstation is called rivets.companyname.com until you discover that there are also workstations called gromets.companyname.com and washers.companyname.com.

The final component of a domain name is either a category or a two‑letter country code. North American sites generally use these categories, though there are sites in Europe using categories, and sites in North America using country codes. The categories are:

·         com: commercial or company sites.

·         edu: educational institutions, typically universities.

·         gov: U.S. government (civilian).

·         mil: U.S. military.

·         org: organizations; originally clubs, associations and non‑profits; currently, many kinds of organizations.

·         net: network sites, including commercial Internet service providers.

·         int: international organizations (rarely used).

These three‑letter codes are top‑level domain (TLD) names. If a domain name ends with a TLD, the second‑to‑last component is the name of the company, organization, or institution.

Many sites use two‑letter country codes instead of TLDs. Some examples are:

·         us: United States.

·         mx: Mexico.

·         ca: Canada.

·         au: Australia.

·         fr: France.

·         ch: Switzerland (Confédération Helvétique).

·         uk: United Kingdom