When someone first learns Jenkins, the workflow often looks deceptively simple: a developer pushes code, Jenkins runs, and the build either succeeds or fails.

That view is useful at the beginning, but it hides most of the concepts that matter once Jenkins becomes part of a real engineering platform. Between the moment Jenkins receives a build request and the moment a build command actually starts running, several components are involved: the Controller, Queue, execution node, Executor, Workspace, and persistent Jenkins state.

Before we install Jenkins on AWS, add build workers, introduce ephemeral agents, or discuss production architecture, we first need a precise mental model of what is actually happening inside Jenkins.

That is the goal of this article.

1. Jenkins Is More Than a Build Server

At a high level, Jenkins is an automation server that orchestrates CI/CD workloads.…