In this chapter, we will look at two fundamental tools of software engineering: source control and deployment pipelines. Source control and deployments are closely linked because the deployment process relies on a stable, traceable, and consistent version of the code, which source control provides. By tracking every change, source control ensures that deployments are based on specific, known versions of the application rather than unverified or ad hoc code. This connection enables teams to automate deployments from particular branches or tags, roll back easily if something goes wrong, and maintain confidence that what’s being deployed has been thoroughly reviewed, tested, and appropriately versioned. In short, source control provides the foundation that makes code reliable and deployable.