What is meant by the term the triple constraint? What are the three elements of the triple constraint and why is an understanding of their relative weight significant in exercising control over a project?

The term ‘triple constraint’ consider to the fact which any project takes place into the envelope of the time this is expected to take, the budget accessible and some understanding of that has to be expressed, delivered as scope, quality or product.

This is important for a project manager to know the balance among the three triple constraint components in her project and this will influence the choices she makes in taking control actions.  Would this, for illustration, be acceptable to cut corners into quality to maintain the costs down or should additional funds be determined to make sure the quality of the deliverables?