Before we get into designing and building our new web business, it is important for us to understand how the Internet works and how Joomla! itself fits into the picture. This information will be critical to us later when we want to make changes to our site, or fix problems with it, because without this knowledge we will have little or no idea where to start.

To help us with this, we will look at:

• The architecture of the Internet
• HTML
• CSS
• Server-side scripting and PHP
• Client-side scripting with JavaScript
• Database work with MySQL and SQL

The architecture of the Internet

The Internet is primarily based off on a client/server relationship, with client computers, mostly people at home or at their office, connecting to web servers, usually as part of browsing a web site.

Because the web servers are physically separated from the client computers, and could be thousands of miles away, Internet interactions are limited to distinct requests and responses to and from web servers. It doesn't happen instantaneously, like with a native application that is running on our computer. Even though some modern web sites and high-speed connections can seem almost to act like a native application, they still operate in the same way as other web sites, via request and response.

This difference is illustrated in the following figure:

When building a web site, the web developer will put all the files needed for the site onto the web server. Then when a person on their client computer visits the web site using a web browser, they don't actually go to the site. The reality is that the site comes to them. The client sends their request to the web server, the web server sends them a copy of all of the web pages and files that are needed to fulfill their request, and then their web browser assembles the files into a presentable web page, as illustrated in the following figure:

Why is this important? Because it is important to realize that when someone is interacting with our web business, they aren't interacting with it live, but only with its copy that was downloaded onto their computer. This will affect how we approach designing, building, and also fixing our web business.