See our Documentation Library for development guides, API reference, and manuals for developer tools.
You should start with our Overview of the GNOME Platform. This presents a high-level overview of the different pieces of the GNOME Platform: libraries to write user interfaces, to integrate with the desktop, to do inter-process communication, use the virtual file system, provide accessibility, and multimedia.
Those areas are listed below with descriptions of what they contain.One can also find some useful books available on the Books page.