Enterprise Project Management is a way of thinking, communicating and working, supported by an information system, that organizes enterprise's resources in a direct relationship to the leadership's vision and the mission, strategy, goals and objectives that move the organization forward.
Simply put, EPM provides a 360 degree view of the organization's collective efforts.
In order to facilitate governance, it has become essential to be able to manage, monitor, and assess the status of all projects (and other assets, of course) in the enterprise, through a set of (preferably uniform) Enterprise Project Management processes, methods and application packages.
They might even select and implement a software system to support Enterprise Project Management.
Once the contents of the portfolio are agreed upon, it is key to constantly scrutinize how the individual projects are evolving in terms of quality, cost and schedule.