The twelve-factor app is a methodology for building software-as-a-service apps. It involves using declarative formats for setup automation, having a clean contract with the underlying operating system, and deploying on modern cloud platforms. The methodology can be applied to apps written in any programming language and using any combination of backing services. The contributors of this document have had experience with the development and deployment of numerous apps, which has allowed them to identify common problems and provide broad conceptual solutions. The document outlines twelve factors that developers and ops engineers should consider when building and managing applications. These factors include things like tracking code in revision control, isolating dependencies, and maximizing robustness. Overall, the methodology aims to improve efficiency and agility in software development.
https://12factor.net/