Continuous integration and continuous delivery, or CI/CD, is the automated path from code change to running software. A developer commits code, the pipeline builds it, runs tests, and, if everything passes, deploys it. The point is to catch problems early and make releases boring. Manual releases are slow and error-prone precisely because humans repeat steps differently each time.
The stages in order
- Build: the code is compiled or packaged, and missing dependencies fail here, early and cheaply.
- Test: automated checks run, including unit tests and basic integration checks, before any user sees the change.
- Staging: the change runs in an environment shaped like production, where configuration problems surface.
- Deploy: the change reaches production, ideally in small steps with a way back if something breaks.
When a pipeline fails, read the failing stage first. It tells you whether the problem is code, tests, configuration, or the deployment itself.