A document that defines exactly what work will be done under a contract — the who, what, when, and how of a project.
A Scope of Work (SOW) is the section of a contract (or a standalone document referenced in the contract) that defines exactly what the service provider will do. It describes specific deliverables, timelines, milestones, acceptance criteria, and often who is responsible for what. It's the "what we agreed to do" document.
Scope disputes are the most common source of service agreement conflicts: the client thinks the scope includes X, the provider thinks X is out of scope. A well-written SOW prevents these disputes by being specific: "design five landing page concepts by June 15" is better than "design landing pages." "Deliver three rounds of revisions" is better than "revisions as needed."
The SOW can be part of the main service agreement or a separate document that the agreement incorporates by reference. The latter approach is useful when you have ongoing work with changing scope — you can issue new SOWs under the same master agreement without renegotiating all the base terms. This is the basis of a Master Services Agreement (MSA) + SOW structure.