# Why Version Control Exists

## The problem: `final.txt`, `final_v2.txt`, `final_v2_ACTUALLY_FINAL.txt`

Before version control, "keeping history" usually meant copying a file with a new name every
time something changed. This fails fast: you lose track of WHAT changed between versions, WHO
changed it, and WHY — and it gets completely unworkable the moment more than one person touches
the same project.

## What version control actually gives you

- **History** — every change, in order, permanently. You can see exactly what a file looked
  like at any point in the past.
- **Reproducibility** — you can recreate the EXACT state of an entire project at any past
  moment, not just one file.
- **Collaboration** — multiple people can work on the same project without emailing files back
  and forth or overwriting each other's work.
- **A source of truth** — one authoritative history everyone agrees is correct, instead of
  "whoever has the newest-looking filename."
- **Rollback** — if a change turns out to be wrong, you can return to a known-good prior state
  with confidence, not by hoping you kept a backup copy somewhere.

## Why copying files isn't version control

Copying `app.py` to `app_backup.py` before making a risky change LOOKS like version control, but
it has none of version control's real properties: no record of WHY the change was made, no way
to see incremental history, no way to combine two people's simultaneous edits, and no
scalability past a handful of files. Git (and version control generally) tracks CHANGES over
time as a structured history, not disconnected snapshots you have to manually manage.

## Instructor Notes

**Lesson goal:** Motivate Git before teaching a single command — students should feel the real
problem (the `final_v2_ACTUALLY_FINAL.txt` pattern) before the solution makes sense.

**Approximate timing:** 10 minutes read; 8 minutes live.

**Discussion question:** "Has anyone ever lost work, or overwritten someone else's work, because
of exactly this kind of file-copying problem?" (Real personal stories land this lesson far
better than abstract description.)