A statement of work is a document that is used in project management and captures and defines different aspects of a commercial project. It details and lays the groundwork for the project plan by setting out things such as, why the project is being carried out, the aim of the project and all project deliverables.
A statement of work is an ancillary document to other commercial documents (such as a master services agreement or terms and conditions for the supply of services, ie a governing agreement). While a governing agreement sets out provisions relating to the entire commercial relationship, the statement of work usually deals with the specifics of a single project.