We've already introduced Spring Security's authentication architecture
in the Technical Overview chapter.
In this part of the reference guide we will examine individual
authentication mechanisms and their corresponding
AuthenticationProviders. We'll also look at how to
configure authentication more generally, including if you have several
authentication approaches that need to be chained together.
With some exceptions, we will be discussing the full details of Spring Security bean configuration rather than the shorthand namespace syntax. You should review the introduction to using namespace configuration and the options it provides to see if they will meet your needs. As you come to use the framework more, and need to customize the internal behaviour, you will probably want to understand more about how the individual services are implemented, which classes to look at extending and so on. This part is more targeted at providing this kind of information. We'd recommend that you supplement the content by browsing the Javadoc and the source itself .
 Links to both Javadoc APIs and browsable source cross-reference are available from the project web site.