The principle that includes “working software is the primary measure of progress” is one of the twelve principles behind the Agile Manifesto. The Agile Manifesto is a declaration of four values and twelve principles that guide the Agile software development movement. The value that corresponds to this principle is “working software over comprehensive documentation”. The principle states that the ultimate goal of any software development project is to deliver working software that satisfies the customer’s needs and expectations, and that any other intermediate or auxiliary artifacts, such as plans, documents, models, or reports, are secondary and should not distract from the main objective. The principle also implies that working software should be delivered frequently and continuously, and that the progress of the project should be measured by the amount and quality of the software delivered, not by the adherence to a predefined plan or schedule. References: Principles behind the Agile Manifesto, Agile Manifesto - Scaled Agile Framework