Terms of reference
Terms of reference describe the purpose and structure of a project, committee, meeting, negotiation, or any similar collection of people who have agreed to work together to accomplish a shared goal. The terms of reference of a project are often referred to as the project charter.
Terms of reference 
Terms of reference show how the scope will be defined, developed, and verified. They should also provide a documented basis for making future decisions and for confirming or developing a common understanding of the scope among stakeholders. In order to meet these criteria, success factors/risks and restraints should be fundamental keys.
Creating detailed terms of reference is critical, as they define the:
- Vision, objectives, scope and deliverables (i.e. what has to be achieved)
- Stakeholders, roles and responsibilities (i.e. who will take part in it)
- Resource, financial and quality plans (i.e. how it will be achieved)
- Work breakdown structure and schedule (i.e. when it will be achieved)
They should include:
- Success factors/risks and restraints.
In a project life cycle 
The "terms of reference" are created during the earlier stages of project management, immediately after the approval of a project business case. They are documented by the project manager and presented to project sponsor or sponsors for approval. Once the terms have been approved, the members of the project team have a clear definition of the scope of the project. They will then be ready to progress with the creation of the remaining project deliverables.
This phrase is often used when describing the task that has been assigned to a consultant or advisor. As such, the consultant or advisor may be engaged via a contract with general terms of engagement that also incorporates the terms of reference that specifically describe the consultant's task.