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published June 7 2004
Geekspeak 101: a beginner's guide to Internet technology
There are easily dozens of different technologies at work on the Web, a virtual alphabet soup of acronyms: HTML, XML, XHTML, DOM, CSS, PHP, ASP, SQL, UNIX ... and on and on and on.
While there are just too many to visit them all, in this issue we will explain the most common Web technologies and their uses. They can easily be divided into three categories:
- client-side
- server-side
- plug-ins
Client-side Technologies
Client-side refers to technologies which are read and acted upon by the client. While 'the client' is most commonly a Web browser like Internet Explorer or Firefox, it could also be a hand-held PDA, a reader or some other device. HTML and Javascript are both examples of client-side technologies. The most common are:
- HTML
- XHTML
- CSS
- Javascript
HTML stands for HyperText Markup Language; it is the lingua franca of the Internet. HTML's purpose is to define the data structure of a Web page, for example headings, paragraphs, lists, etc. It is also often used (incorrectly) to define the appearance of Web pages.
I say incorrectly because theory holds that we should keep separate the data (text, pictures, etc.) and the information that tells the browser how the data should appear. This concept is referred to as the separation of content and presentation.
Enter XHTML and CSS. XHTML is the latest implementation of HTML. It's sole purpose is to make a clean and final break between content and presentation.
XHTML stands for Extensible HyperText Markup Language. Much like original HTML, XHTML defines the structure of page data. CSS stands for Cascading Style Sheets. CSS defines how the data will appear — the presentation. Working together, XHTML will define the beginning and end of a paragraph with <p></p>; CSS will contain the presentation information, telling the browser that the paragraph should be displayed in 14-point arial font.
Javascript is a completely different animal. As the name suggest, Javascript is a scripting language (a lightweight programming language). While HTML, XHTML and CSS are concerned with content and presentation, Javascript was designed to add interactivity to Web pages, like creating menu rollovers and pop-up windows, verifying form data and creating dynamic interfaces and content.
Server side Technologies
Server-side is the opposite of client side. Server-side technologies are acted upon by the server before ever getting to the client. A database is a good example of a server-side technology. The most common are:
Server-side technologies are often referred to as back-end technology, or just simply the back end. Their front-end counterpart would be the client, or browser.
SQL stands for Structured Query Language. MySQL, officially pronounced "My-eS-Que-eL" (not "my sequel"), is the world's most popular open-source database.
The purpose of any database is to store information, for example usernames, passwords, pictures, stories or any other kind of data. To retreive this data from the database and present it to the client, we need some sort of programming language that can communicate with the database and output HTML or XHTML for the browser to read.
The most popular language used for this is PHP, an open-source scripting language. Along with handling our database tasks, PHP can also do much more sophisticated jobs like communicate with the server, read through directories, create and edit images and more.
A typical scenario might look like this: your browser makes a request for a story at xyznews.com. Using PHP (or perhaps the MS-flavoured ASP), the page you requested checks your username and password against the database. If you credentials are correct, PHP will ask the database for the story you requested and send it, along with other page data, marked up in HTML for your browser to read. If you are not logged in or your credentials don't match the database, PHP will send the HTML markup for a sign-in page.
Plugins
Plug-in technology enhances the basic functionality of the Web browser. While plugins are not part of the original browser install, they are designed to work in conjunction with the browser. They are literally hundreds, some of the most common are:
- Flash
- Acrobat/PDF
- Quicktime
- Java
The more popular plugins, like Flash and Quicktime, are used to play multimedia content in the browser. But there are many other plugins designed to help accomplish more mundane task, like the Google toolbar for searching or Acrobat for reading PDF formatted documents.
Flash is probably the most ubiquitous. Originally designed to create low-bandwidth animation, Flash now includes video capabilities and a scripting language all its own. Much of the animation on the Web today uses Flash.
PDF stands for Portable Document Format. The Adobe Acrobat plugin is used for reading PDF-formatted documents in a Web browser. It allows for consistent formatting across platforms and is widely used for accurate printing of documents.
Quicktime is a popular plugin that allows for playing video and other interactive content. Created by Apple computers, Quicktime is the format of choice for Web video.
Java is a bit different than the other plugins in that Java is a robust, object-oriented programming language capable of just about anything. In a Web browser Java usually comes in what are called applets, or small, stand-alone Java applications. Java is often used to create Web-based applications like chat rooms and online gaming.
For questions or comments on this article write to webPundit at k4media dot com.
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