During the planning phase, the DevOps team ideate and clarify application features, capabilities, quality definitions, security definitions and user definitions. The product owner in the team builds and manages the product backlog; tools are set up for agile delivery.
DevOps teams participate in Sprints, and the shippable software is built iteratively and incrementally. During the development phase, teams innovate rapidly, build software, test them for functionality, stability, scalability and security. The teams strive to automate manual steps, and the built software is continuously integrated through a specific practice by the name Continuous Integration (CI).
The built software is deployed into the production environment with consistency and reliability in the Delivery phase. The delivery phase encompasses deployment, configuration and any infrastructural change required by the piece of software built. Automation at this phase makes the process controlled, repeatable and scalable.
In the operation phase, teams maintain, monitor, and troubleshoot the deployed software in the production environment. The golden phrase for the teams here is "zero downtime". Teams look for potential issues that might affect the application and fix them before it implodes.