General Introduction

The Internet is often referred to as the "Network of Networks" which may sound redundant.  To appreciate where the Internet came from, where it is today and where it may be headed requires a basic familiarity with computing terminology. 

Inside of your computer is a device called a bus which serves to connect different devices - disk drives, tape drives, video boards, modem boards, etc. Each of these devices has an address which allows packets of information to be distributed to the appropriate device(s). Communication is facilitated by the bus and takes place according to a protocol (set of instructions). Information is packaged into packets which have an origin and a destination. Thus, within your desktop computer there are sets of linkages which allow information to flow from a source at a known address to a destination at a known address.

The key to connectivity on the Internet is a system for addressing each individual computer that is part of the Internet. Each address can be written in numeric ( or alphanumeric form (JCButler.GeoSc.UH.Edu). These addresses (IP or Internet Protocol) allow your machine to serve as the origin of a request or as the destination of a request from another machine on the Internet. Through your system coordinator you can request a unique (or fixed) address for your machine. Many systems have a "pool" of available IP addresses that are assigned upon demand (asynchronous) to your machine. As long as you are "on line" the address is associated with your machine. When you log off the address is returned to the pool for reassignment. The next time you log on a new number may be drawn from the pool or, if you are unlucky, there may be no addresses left to assign and you will be denied access. If you intend to be a "regular user" you should request a fixed IP from your system administrator.

Once your machine is connected to the Internet you can take advantage of a number of protocols or sets of information processing instructions. A very common protocol uses Transfer Control Protocol/Internet Protocol (TCP/IP). Software based on TCP/IP protocol allows the user to send electronic mail or e-mail (such as Eudora), send and receive files using File Transfer Protocol (FTP, such as Fetch), locate information about Internet users (Finger), receive text, image and sound files (Turbogopher, Gopher), read and post responses to USENET (news, NewsWatcher), or easily navigate from site to site using Hypertext Transfer Protocol (HTTP, Netscape, Explorer, or Mosaic) on the World Wide Web (WWW).

A relatively common misconception used to be that each software package works on or belongs to a unique network. Thus, the user may refer to the "Gopher Network" or the "News Group Network" or the World Wide Web Network. Programs like Netscape are clients which use the HTTP protocol to send requests to servers (or daemons). A server is an application which allows the machine on which the application is installed to process requests from numerous clients; of course, each of the potential clients must know the IP address of the server. A number of servers may be installed on a single machine and the same machine can function as a client by running specific software. My Centris 650 at the University of Houston used to function as a WWW server (running MAC HTTP) and as an FTP server (running FTPd). While the Centris responds to HTTP and FTP client requests I could run Netscape and interact with other HTTP or FTP servers (including my own machine!) simultaneously. Thus, there is really only one "Internet" with hardware consisting of various types of cables and wires and microwave dishes, etc. Through the IP addressing protocol each properly connected machine can take advantage of a number of protocols by running the appropriate software applications.

In order to provide a framework for addressing "nodes" on the Internet, the Uniform Resource Locator (URL) was introduced. In general, a URL has the following form.

The first part of the URL (http://) identifies the protocol and the second part ( provides the IP address of the server.
The file that has been requested -- index.html is in the nsm subdirectory of the academics directory.

If you are using Netscape the operation - command L - opens a box in which the address can be typed (actually, with Netscape you can eliminate the http:// part of the address given above). This is the location of the home page of the College of Natural Sciences and Mathematics at the University of Houston. If this is your first time using Netscape remember that "clicking" of the Back Arrow at the top of the screen (pointing to the left will take you back to the previous site (in this case, this page). Or, you can pull down the GO menu and click on the location that you want to return to. Double clicking on the highlighted text above (the colored text) sends a request to the server. Unless the maximum number of simultaneous users is exceeded or the server is "down" you should receive our home page. Take some time and look around this home page. [Remember to use the back arrow to return to this introduction!].

You can control the color of these "hot links" by setting your Preferences at the top of your screen under Options. You can set one color for a link that you have not followed and another color for a link that has been followed (by someone using your copy of Netscape (or Explorer, or Mosaic). For example, many users prefer blue for an non followed link and red for a followed link. You can even control the length of time (in days) that a followed link stays red. This is very helpful as it will allow you to look at a list of resources and see how many of them have been followed. If you haven't already done this, take a few minutes to set the fonts and font size, enter your email address, your email post office address, etc. You can always make these changes as you become familiar with different Internet protocols.

As noted previously, there are a number of software applications for each of the protocols. Rather than use a different application for each protocol (for example, Fetch for FTP and Turbogopher for Gopher protocol), you can use Netscape (or any other WWW browser) to access these different servers.

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