Git
Stage 2 of Programming4 lessons
Git keeps your project's history: every version, who made it and why. Four lessons, in order: committing versions, writing their messages, looking back and working on branches. All on your computer; GitHub comes after.
Lesson 2.5.1: Committing versions
Git saves versions of a folder. Each version you commit to the history is a commit, with its message.
Lesson 2.5.2: Messages
A commit message is read by someone who wasn't there. With a shared format, it makes sense at a glance.
Lesson 2.5.3: History and going back
What you save with Git can be looked at and recovered: the history, the changes and any earlier version.
Lesson 2.5.4: Branches
A branch is a separate line of work: you try something without touching what already works.