1. Introduction

Many web sites are designed to allow the visitor to interact with the server in some way.

For example, filling out a form and sending off the details to the server. Or a shopping site that allows customers to build up a shopping cart and then pay for it through a payment gateway.

The people who created the website wrote code to handle all of these requests. There are two ways that these requests can be processed - either on the computer of the person making the request, or on the server itself.

• Client side processing
• Server side processing

Since each is useful in different situations (which we will discuss on the following pages), you will often find websites that include both client-side and server-side processing for different things.

Web pages that don't allow for any requests by the users are called static pages. Pages that do contain processing code are called dynamic pages.