Integration Management
If each little part of the project is a tree, Integration Management is the entire forest. It focuses on the larger tasks that must be done for the project to work. It is the practice of making certain that every part of the project is coordinated.
In Integration Management the project is started, the project plan is assembled and executed, the work is monitored and verification of the results of the work is performed. As the project ends the project manager also performs the tasks associated with closing the project.
A project manager must be very good at Integration Management or the project may very well fail. Other knowledge areas are also important, but Integration Management is the area that requires the most management and control of the entire project.