What is a Statement of Work (SOW)?
The statement of work is the narrative description of the products, services, or results to be delivered — in procurement, it's the section of the contract that tells the seller exactly what the buyer is buying. Clear SOW, clean contract; vague SOW, change-order festival.
Flavors matter in practice: a design SOW specifies how (buyer carries performance risk); a performance SOW specifies outcomes and lets the seller choose how (seller carries more risk).
Worked example
A city's SOW for streetlight replacement specifies: 4,200 fixtures to LED, photometric levels per the attached standard, work windows 22:00–05:00, traffic control per municipal code, disposal certificates required. The bidder who assumed daytime work and no disposal costs can't claim surprise — it's all in the SOW.