The CI/CD Pipeline: End-to-End Flow
What CI/CD names
CI Engines: GitHub Actions and Jenkins
Both tools run a defined sequence of steps when a trigger fires. They differ on one axis that drives almost everything else: who operates the machine. GitHub Actions is managed by GitHub and native to a GitHub repository; Jenkins is a server you host yourself, tied to no particular version-control system.
Packaging: Docker and the Registry
Packaging is the seam between CI and CD. CI has proved a change builds and passes its tests; packaging turns that result into a single, portable unit that will run identically on a developer's laptop, a CI runner, and a production server. The unit that achieves this for most modern services is a container image, and Docker is the dominant tool for producing and running it.