Session 1 · Meet Git#

⏱ about 45 minutes · 🧰 you need: the Setup done

The big idea#

Imagine writing a long report. You save a copy before every big change: report.docx, report_final.docx, report_final_v2.docx, report_final_v2_REAL.docx. Two weeks later you cannot remember which one has the paragraph you deleted by mistake. Now imagine ten people doing that to the same folder.

Git is a time machine for a folder. You tell it “remember how the project looks right now”, and it keeps that snapshot forever, with a note about who saved it and why. Later you can look at any snapshot, compare two of them, or go back to one.

Files with and without Git Without Git you copy files and invent names; with Git there is one file and Git remembers every version. WITHOUT GIT report.docx report_final.docx report_final_v2.docx report_final_v2_REAL.docx which one is the latest? WITH GIT report.docx one file in your folder git log → every version, who, when, why git restore → go back any time Git is a time machine for your project folder
Without Git you copy files and invent names; with Git there is one file and Git remembers every version.

Everyday example: a photo album. You do not keep every photo loose on the table. You pick the moments worth remembering, stick them in the album in order, and write a caption under each. Git’s album is called a repository, each photo is a commit, and the caption is the commit message.

1. Three words that confuse beginners#

Word

What it really is

Version control

The idea: a system that records changes to files over time.

Git

A free program on your computer that does version control. It works offline.

GitHub

A website that stores Git repositories online so teams can share them. GitLab and Bitbucket are similar sites.

Important

Git is not GitHub. Git is the tool; GitHub is one place to host your Git projects. You can use Git for years without GitHub.

2. Why teams use Git#

  • Undo anything. Broke the app at 5 pm? Go back to the 4 pm snapshot.

  • Know who changed what and why. Every line has an author and a message.

  • Work in parallel. Each person works on their own branch (a private line of work) and the branches are merged later (Sessions 5 and 6).

  • Work offline. The whole history lives on your computer. Internet is only needed to share.

  • Try ideas safely. Experiment on a branch. If it fails, throw the branch away.

3. A commit is a snapshot#

A commit is a snapshot Each commit stores a snapshot of the project plus who made it, when and why, and points to the commit before it. commit a1b2c3d "Add homepage" snapshot · author · date commit e4f5a6b "Add contact page" snapshot · author · date parent commit c7d8e9f "Fix typo in title" snapshot · author · date parent each commit points to the one before it: that chain is your history
Each commit stores a snapshot of the project plus who made it, when and why, and points to the commit before it.

A commit records:

  1. a snapshot of every tracked file at that moment,

  2. who made it and when,

  3. a message saying why,

  4. a pointer to its parent, the commit before it.

Because each commit points to the one before, commits form a chain. That chain is your project’s history. Each commit has a long unique ID such as a1b2c3d4e5f6... (usually shortened to the first 7 characters).

Note

Git does not store “the differences”. It stores snapshots, and is clever about not duplicating files that did not change. That is why switching between versions is nearly instant.

4. The three areas (the model to remember)#

This one picture explains most of Git. You will meet it again and again.

The three areas of Git You edit in the working folder, git add moves changes to the staging area, git commit saves them in the repository. Working folder your desk files you edit Staging area the packing box what goes in the next save Repository (.git) the photo album permanent history git add git commit restore unstage edit → add → commit : the three-step rhythm of Git the staging area lets you choose exactly what goes into each save
You edit in the working folder, git add moves changes to the staging area, git commit saves them in the repository.

Area

Everyday comparison

What lives there

Working folder

Your desk

The actual files you open and edit.

Staging area (also called the index)

A packing box

Changes you have chosen to include in the next save.

Repository (the .git folder)

The photo album

Every commit ever made.

Saving in Git is a two-step action: first git add puts changes in the box, then git commit seals the box and files it in the album. The extra step lets you decide exactly what goes into each snapshot.

5. Try it: check your install#

cd ~/git-lab
git --version
git config user.name
git config user.email

git version 2.43.0
Asha Kumar
asha@example.com

6. Getting help#

Git has built-in manuals. They are long, but the first lines are handy:

git help commit      # opens the full manual (press q to quit)
git commit -h        # a short summary of options

Common mistakes#

Mistake

Fix

Thinking Git and GitHub are the same

Git runs on your computer. GitHub is a website that hosts repos.

Expecting Git to save automatically

Git only records what you commit. Editing a file does not save it into history.

Using a name or email you do not want public

git config --global user.name ... changes it for future commits. Old commits keep the old values.

Hands-on exercises#

Tryout 1 · Check. Print your configured name and email.

Answer 
git config user.name
git config user.email

Tryout 2 · Explain. In your own words, write one sentence each for: repository, commit, staging area. Compare with the tables above.

Answer

A repository is the project folder plus its complete history (stored in .git). A commit is one saved snapshot with an author, date and message. The staging area is where you collect the changes you want in the next commit.

Tryout 3 · Challenge. Find out which editor Git will open for commit messages, and see where that setting is stored.

Answer 
git config --show-origin core.editor

file:/home/asha/.gitconfig	nano

Global settings are stored in ~/.gitconfig (a plain text file you can open).

Recap#

  • ✅ Git = a time machine for a folder. GitHub = a website that hosts Git repos.

  • ✅ A commit is a snapshot with an author, a date, a message and a pointer to its parent.

  • ✅ Three areas: working folder → staging area → repository.

  • ✅ Saving = git add then git commit.

Next: Session 2 · Your First Repository.