The project management triangle is a model of the constraints of project management. While its origins are unclear, it has been used since at least the 1950s. It contends that:The quality of work is constrained by the project's budget, deadlines and scope (features). The project manager can trade between constraints. Changes in one constraint necessitate changes in others to compensate or quality will suffer.

Project management is the process of leading the work of a team to achieve all project goals within the given constraints. This information is usually described in project documentation, created at the beginning of the development process. The primary constraints are scope, time, and budget. The secondary challenge is to optimize the allocation of necessary inputs and apply them to meet pre-defined objectives.