The research proposal is a key element in you PhD application and a quite detailed description of the academic content of the proposed research project. This means you should present the key questions that you intend to pursue, the theoretical framework and methodology that you plan to adopt as well as explain how your planned thesis will add to already existing research.
The research proposal should also comprise a preliminary bibliography and a preliminary study plan outlining how you plan to complete the study programme. This includes the work on the PhD thesis, staying at a different -mainly foreign - research institution, participation in courses, conferences etc.
On the websites of the respective departments you will finde more information about research proposals and individual study plans (view the box on your right).
You can read more on the page about applications in response to an advertisement.