What a branch really is

A branch is just a movable label

Here's the demystifying fact of the whole course: a branch is a tiny file containing one commit hash. That's all. A 41-byte sticky note saying "this line of work is currently at commit c7d8e9f."

You've had a branch all along: main, created automatically by git init in lesson 2-1. Every time you commit, Git creates the new snapshot and then moves the current branch's label forward onto it. The label follows the work.

And HEAD from lesson 3-1? Normally HEAD points at a branch, and the branch points at a commit. "You are on main" literally means HEAD → main → c7d8e9f.

Why this matters: because branches are just labels, creating one is instant and free. Engineers spin up a branch for every experiment, feature, and bug fix, because trying ideas costs nothing and main stays untouched until the idea proves itself.

See the file with your own eyes

This isn't a metaphor to take on faith — the file is really there. Inside .git, every branch is one plain text file at .git/refs/heads/<branch-name>, and its entire contents are one commit hash. cat it and you've read a branch.

Our sandbox has no Git installed, but the layout is just folders and files, so you can recreate it exactly and prove to yourself how little a branch is.