The Project Management Triangle
Project Communication Management
Phases and Methods of Project Management
You can visualize project work in many ways, but our favourite is what's sometimes called the project triangle:he interrelationship of time, money, and scope. If you adjust any one of these elements, the other two are affected. For example, if you adjust the project plan to shorten the schedule, you might increase costs and decrease scope.
(techincal definition "scope": the combination of all project goals and tasks, and the work required to accomplish them; the scope translates into the timeline and budget)
Project management gets most interesting when you have to balance the time, cost, and scope constraints of your projects—"balance" as on a high wire.
Scope, Time and Cost, are the three essential elements of any project. To succeed as a project manager, you'll have to know quite a bit about how all three of these constraints apply to your projects. You need a tool to help manage them.
In Project Execution and control phase of project management we can adopt a more complex matrix of balance that includes the element of quality: CSSQ is the acronym for a project’s linked quadruple constraints Cost, Scope, Schedule, and Quality.
See The 9 topic areas of project management knowledge