At the end of the day, you have to actually create and deliver the product. This means you have to “procure” it and its constituent parts. This procurement can be via contracts with contractors, purchase orders with vendors, or perhaps the bits and pieces of the widget are to be fabbed/created in-house by your project team. Regardless, one of your key jobs as a project manager is to ensure these procurements occur in the correct order, on budget, on schedule, and that the delivered scope/quality is up to the appropriate standards. This in effect is where the rubber of the golden triangle hits the management road.
The following are links to specific posts and pages on this all-important topic of Procurement Management