spec

Spec is short for specification, a detailed description of the requirements, design, behavior, or characteristics of a system, product, or process. A specification provides the basis for development, testing, procurement, and compliance. It may be functional, describing what the system should do, or technical, detailing materials, performance, interfaces, tolerances, and standards.

Specifications are used across many industries. In engineering and manufacturing, they define dimensions, materials, performance metrics, and testing methods, often appearing as a spec sheet or a formal document that accompanies a product. In software and electronics, API specifications and interface specs define how components interact and may be maintained as living documents during development. Specifications also guide validation, quality assurance, and regulatory compliance.

In film and publishing, “spec” commonly refers to a spec script—an original screenplay or manuscript written without a buyer or commission in the hope of selling it. Spec work contrasts with writing produced under contract or assignment and has played a key role in the careers of many writers and studios.

In broader usage, to spec or to meet specs means to fulfill defined requirements. Specifications are typically aligned with standards and regulatory frameworks, and they guide procurement, verification, and acceptance testing.