The purpose of the Control phase is to assure that the decisions are implemented as intended, i.e., planned results are achieved on schedule and within budget.
Information technology evolves rapidly and so do organizational needs.
The Control phase helps to assure continued alignment with strategic goals and business objectives. You will recall that during Selection, some very basic and important questions were asked and answered. This is how we will accomplish it. This is how much we will pay for it. This is when we intend to do it.