This page contains advanced material and background material that may be of interest if you are want to build GeoTools for source or take it appart and see what makes it tick.
Why would you want to do this? We we hope it is because you are interested in joining the project either by creating your own module or diving in and working on the core modules.
This material is also of interest if you are embeding the library in a larger application and would like to make use of the GeoTools plugin system and configuration options to “teach” GeoTools how to work with your application.