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Source Control

Before version control, teams shared code by copying folders: project, project_final, project_final_v2. Files got overwritten. Parallel work was impossible. Changes disappeared.

Git solved this in 2005 and became the universal standard. Every modern engineering workflow is built on it.

What this section covers​

Git — How the distributed model works, what commits actually are, how branching enables parallel work, and what is happening under the hood when you run git commit.

GitHub workflows — How teams use Git collaboratively: remote repositories, pull requests, code review, branch protection, and merge strategies.

Why the mental model matters​

Most engineers learn Git by memorizing commands. They git add, git commit, git push without understanding what they're doing. Then something goes wrong — a merge conflict, a detached HEAD, a rebase gone wrong — and they have no way to reason about it.

Git has a simple, elegant data model. Once you understand it, the commands make sense. Merge vs rebase is obvious. Why rebase rewrites history is obvious. Why git reflog can recover lost commits is obvious.

Learn the model, not just the commands.