Introduction to the INTERNET

In order to understand what the "Internet" is, it is important to understand what a simple "network" is. The information contained below will discuss the important aspects of "networks" and the "Internet". There will be a "Review Questions" sheet that will accompany this lesson. Use the sheet as a study guide, but don't just answer the questions. Read the entire material contained here. Many students just try to answer the questions "out of context". That means they skim through the material to find only the answers to the questions. This is a poor way to approach this type of learning. Remember, you are the person responsible for learning this material. This can only be presented to you. You must be the one who takes advantage of it.

Computer Networks

A "computer network" is a fancy term for the technology of connecting one computer to another. Sometimes, it is desirable for more than one user to access and work on the same file. This can be accomplished by using special hardware and software. The hardware is a special type of computer card that is inserted into the computer or integrated into the design of the computer's motherboard. This type of hardware is referred to as a "network interface card (NIC)". Once the card is inserted into the computer, the user installs special software. This software is only useful for communicating with another computer, so the computer is connected with a cable to the other computer through the NIC's. This setup allows for communication between the two. Sometimes there is very little distance between the two. They may actually be in the same room. However, there is sometimes a need to connect two computers over great distances. This differentiates the difference between two basic types of computer networks called "Local Area Networks (LAN)" and "Wide Area Networks (WAN)". The difference is quite simple. A LAN consists of computers connected by cables to each other. Sometimes the distance is over a fairly large area in a very large building. However, with a WAN, the computers use transmission devices and transmission lines to send information to each other, like a telephone system.

The major drawback, was that computer networks were often set up with specialized hardware and software that would not allow the interconnecting of the separate networks. A special technology was developed that allowed these different networks to interconnect with each other.

The Internet

The "Internet" is a huge computer network that connects millions of computers and computer networks around the world. This is done through the use of special computers and computer software. Originally, the information transferred consisted primarily of text. The Internet expanded to a contain a graphic-based component called the "World Wide Web (WWW)". This led to a tremendous growth in the amount of users accessing this new technology. It continues to grow daily.

The roots of the Internet can be traced back to approximately 1969. The persons responsible for its beginnings were the United States Department of Defense. Their goal was to set up a communications "network" to continue communications in the event of a natural disaster or attack. They wanted to be able to have computers able to "talk" to each other over great distances.

The "Internet" uses special computers called "routers" to connect LAN's and WAN's of different types. These computers depend on a shared set of rules that describe how to transmit data. This set of rules is called a "protocol". The software protocol that was developed actually consists of two sets of protocols called "Transmission Control Protocol (TCP)" and "Internet Protocol (IP)".

"Internet Protocol" breaks up the information and puts it into software "packets" that can be moved across networks.

"Transmission Control Protocol" works together with the IP protocol to guarantee that information is transmitted correctly across the Internet.

Servers and Clients

Every computer program that operates on the Internet is either a "server" or "client".

A "server" offers a service to other machines on the network. For example, a "file server" contains files of interest to may users on a particular network. The service it offers is the storage and retrieval of files for the users.

A "client" requests a service from the server. The computer uses specialized software to request a file from the server. The request is processed, the information or file found, and the server then sends the information requested to the client. The method used for this transfer of information is the "protocol".

The World Wide Web

The "World Wide Web" is the fastest growing segment of the Internet. It has a "graphical interface". This means that the software used to communicate on the Web has the capability to not only display text, but it can also display pictures, sounds, videos and animations. This has led to tremendous growth in the commercial use of the World Wide Web for presenting interactive information and advertising. The growth of business conducted on the Web is expanding daily. This is called "e-commerce".
The World Wide Web has many uses. It is primarily used to access information. This is because of limitations for sending information. All the information on the Web has to be converted and sent out over transmission lines. For most users, the transmission lines are ordinary telephone lines. The information sometimes moves very slowly across these connections. Therefore, as communications technology increases, the amount of information sent will come to include feature length films and television broadcasts. That has already begun on a limited scale.

Web Pages

The basic document of the World Wide Web is a "web page". These pages are primarily created using a special computer "language" called "HTML (Hypertext Markup Language)". The "language" basically consists of normal text, described by "tags". "Tags" are commands that are interpreted by the "web browser" software. These commands describe to the software how to display the information. For example, the word "bold" shown here is darker than the rest of the words, because the HTML tag has told the "browser" (your Internet Explorer or Netscape Navigator) to display it in bold text.

Web Sites

A "web site" is a collection of web pages that are linked together and stored primarily on one computer. The pages are "linked" together using special software commands called "hyperlinks". "Hyperlinks" usually consist of places on a page that can be "clicked" with a mouse to connect or move to another page. The hyperlinks do not have to consist of only words. They can be pictures or "hotspots" on a larger image. "Hotspots" (also called "image maps") are areas on a picture or graphic that act as a link to another page when "clicked" on. This "linking" of pages is the primary means of navigating the World Wide Web. This is sometimes referred to as "surfing" the Web.

Web Browsers

"Web browsers" are software programs that allow the user to access pages on the "World Wide Web". These programs are constantly evolving to keep pace with the technology for displaying information on the Web. The browser navigates through the World Wide Web and displays pages. The browser requests a page from a server based on its Internet address (IP Address). It then gets the page from the server and displays it on the users screen. Depending on the age of the browser, it may be unable to display certain web pages. The constantly evolving nature of HTML and other page description languages such as Java sometimes outpace the technology of web browsers. This results in certain computers unable to display newer web pages. This is an important consideration for anyone who designs web pages, since in order to reach the widest amount of computer users, one may have to design several versions of a particular page or even a whole site.

Another important part of browser technology is referred to as "plug-ins". "Plug-ins" allow certain types of animations and programs to run inside the browser. This sometimes is the major cause of web page incompatibilities. Users should try to keep abreast of upgrades in both browser software and plug-in technology.

Hyperlinks and Uniform Resource Locators

As discussed above, the most common way of navigating from page to page is called a "hyperlink". A hyperlink may consist of text or an image. When clicked on, the server sends a different page to be displayed in the browser. Although most people refer to "going to a Web page"' the user goes nowhere. The user clicks on a "hyperlink" that requests to be connected to a different server, which when connected, requests a file from that server, and the file is sent to the user to be displayed in the user's browser.

Hyperlinks are described in the HTML for a page through the use of a "Uniform Resource Locator (URL)". A "URL" gives the location of a file on the World Wide Web. It is basically a type of address for the file. URL's are based on a protocol used by web browsers and servers. This protocol is called "Hypertext Transfer Protocol (HTTP)". "Http" are the letters that are normally seen in the first part of a URL. Most hyperlinking is done by using the HTTP protocol. For example, "http://www.microsoft.com" is a URL. By clicking on this hyperlink, you will be connected to a computer network operated by the Microsoft corporation.

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