A contract that establishes the standard terms for all future work between two parties, with individual projects governed by separate Statements of Work.
A Master Services Agreement (MSA) is a contract that sets the baseline terms governing all work between two companies. Rather than renegotiating payment terms, IP ownership, liability limits, and confidentiality for every project, you establish those terms once in the MSA and then execute short Statements of Work (SOWs) or purchase orders for each individual project.
MSAs are efficient for ongoing relationships. If you're a design firm that does multiple projects per year for the same client, negotiating an MSA once means individual project SOWs can be as simple as "Project: Logo refresh, Deliverables: 3 concepts by X date, Fee: $5,000." All the legal machinery is already in place.
The MSA governs the relationship at the master level; the SOW governs a specific engagement. If there's a conflict between them, MSAs typically specify which document controls (usually the SOW for project-specific terms, the MSA for everything else). Understanding this hierarchy matters when a client's legal team sends over their version of an MSA — their version will be written to favor them, and you need to understand what you're agreeing to before the relationship begins.