Okay, let's start getting into the thick of things. If you are reading this, you probably already have some conception of what a web application is and does. You might even be tasked with setting up a development environment at your office to start producing web applications in support of your business. However, even if you are totally new to the field, don't worry.
Web applications are actually pretty simple conceptually.
Massage Data - Processing almost always involves playing with data on the server. The user-defined request specifies how the data should be played with. Transmit Query Results - The processed data is now returned to the client. Client Side Processing - Finally, the returned data is displayed to the user. Display might be as simple as interpreting HTML, or as complex as performing calculations, sorting, or other manipulations of the data.