Working software is the primary measure of progress.— agilemanifesto.org/principles
In Chapter 3: Continuous Delivery, we talked about techniques like continuous integration and continuous deployment that ensure that new working software is being delivered not just frequently but continuously. The authors of the agile manifesto clearly point out in this principle that having actual working software is much more valuable than say having a lot of documents that describe some software system that still hasn’t been integrated enough to be running. ...