The later parts of this guide provide an in-depth discussion of the framework architecture and implementation classes, which you need to understand if you want to do any serious customization. In this part, we'll introduce Spring Security 3.0, give a brief overview of the project's history and take a slightly gentler look at how to get started using the framework. In particular, we'll look at namespace configuration which provides a much simpler way of securing your application compared to the traditional Spring bean approach where you have to wire up all the implementation classes individually.
We'll also take a look at the sample applications that are available. It's worth trying to run these and experimenting with them a bit even before you read the later sections - you can dip back into them as your understanding of the framework increases. Please also check out the project website as it has useful information on building the project, plus links to articles, videos and tutorials.