There are 7 themes that are incoorporated within all PRINCE2 projects. It is important to balance them effectively.
Themes can be tailored 'up' or 'down', meaning that additional documentation can be introduced for complex / high risk projects, or it can be reduced for simple, low risk projects.
These themes describe the aspects of project management that must be addressed continually. A professional project manager will give these themes attention in an ongoing fashion.
The themes are designed to link together effectively, this is where the strength of these themes come from. The themes address the chronological flow of the project