Control is the process of monitoring evaluation, and comparing planned results with actual results to determine the progress of project toward the project cost, schedule, and technical performance and apply necessary changes to maintain the plan.
It is usually budget, schedule, and quality of the project that needs to be monitored. However, PM needs to define which specific characteristic of the golden triangle and how that particular concept is to be controlled. Then, the boundaries, within which the controlled should be maintained, should also be established. The risks are monitored and controlled and project progress is continuously evaluated and reported.