Basic Concepts of the World Wide Web


The World Wide Web ("affectionately" called "the Web") is a collection of information stored on computers that are connected to the Internet all over the world. The information can be any type such as text, graphics, audio, and video. The difference between the Web and other types of Internet features is that the Web uses an approach to link material together known as "hyperlinks." When these links are text-based, they are called "hypertext."
 
 

To know how the Web works, the following concepts are helpful:


HTML

HTML (HyperText Markup Language) is a language for marking hypertext links and other important features of a document. If you want to construct your own web page, mastering HTML is the first step. Don't worry, homepage construction is not as difficult as you may think. When I first saw an impressive homepage two years ago, I could not help respect the authors for their work. But now I realize that it is really a relatively easy task to construct a basic but attractive homepage. Of course there are many advanced features such as Javascript, VBScript, Java Applet, ActiveX control and CGI technology (such as PERL scripting, Server Side Include) which still require a lot of knowledge and work. But it's possible to create a very nice homepage without resorting to these advanced features. Then, later, if you're interested, you can move on to learn some of the higher-level capabilities which are available.

 If you know nothing about HTML, you can reference A Beginner's Guide to HTML , a classic and simple tutorial which comes from the home of the original web browser Mosaic - NCSA. Personally, I love NCSA's web site, since they are an excellent source of information for both beginning and experienced Web developers. 


URL

URL (Uniform Resource Locator) is a naming system that compactly describes the location of every resource on the Internet and the protocol to retrieve it.

For example "http://www.cs.uh.edu/~zsyu/me.html" is an URL. It includes three parts:

  1. Transfer Protocol or Scheme - here "http" which stands for HyperText Transfer Protocol
  2. Domain Name (Server Name) , as "www.cs.uh.edu", which is the alias name for "rodin.cs.uh.edu", the web server at the Department of Computer Science of UH.
  3. File path name , here is "/~zsyu/me.html"
Please note that usually the Domain Name is NOT case sensitive but the File Path name is, especially in UNIX-based server systems. This is one of the common problem may confuse some start users.

For more information about URL,visit NCSA again at A Beginner's Guide to URLs


Web Browser (Web Client)

A web browser is a program which combines a variety of information retrieval abilities under one interface, make it easier to retrieve and use resourses. Netscape, Microsoft Internet Explorer and Mosaic are the three most widely used web browsers. It is most likely that you are using one of these three browsers to read this tutorial.

The first graphical web browser was Mosaic, developed by Marc Andreeson (now vice president of Netscape Inc.) when he was an undergraduate in NCSA. Other graphic browsers include:

Web Server

A Web server is a program that runs on a computer connected to the Internet. The Web server watches the Internet connection and waits for requests from the Web browser for HTML an document. When it receives a requests, it finds the HTML document and sends it back to the browser that requested it.

A Web server provides four major functions:

NCSA httpd server, Netscape server and CERN server are currently the three most commonly used servers. 

Client/Server System and Protocols

The Web is build on a client/server model basing on a request/response paradigm. A server is like the proprietor of a general store; it waits for a client to come in with a request. A client is like a customer who walks into the store and asks for one or more items in a grocery.

Clients and servers communicate with each other using a common protocol. A protocol is a collection of rules that must be complied with by both sides when they communicate with each other. The HyperText Transfer Protocol (HTTP) is the protocol used by The Web. 


HTML Editors

You can use any text editor, such as Notepad , Wordpad or vi, to create and edit your HTML files. Some "What You See Is What You Get" (WYSIWYG) editors are available (e.g., Microsoft Frontpage, Internet Assistant ,Netscape Page Composer, HotMetal, HotDog, Adobe PageMill,etc). Some of them are free. For example, the Netscape Page Composer is one part of the latest Netscape Communicator package. It is a good tool to create your web pages. Of course, you can select online listing of HTML editors (organized by platform) by yourself. 
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