Introduction to Git

Git is a distributed version control system (DVCS) created by Linus Torvalds in 2005 to manage Linux kernel development. Today it is the industry standard — virtually every software team uses Git to track code changes, collaborate, and deploy software.

Why Version Control? link

Without version control:

• “Final_v2_REAL_final.js” file naming chaos
• No history of who changed what and why
• Fear of breaking working code — no easy rollback
• Painful collaboration — emailing zip files

With Git:

• Complete history of every change
• Branch to experiment without affecting main code
• Merge work from multiple developers
• Revert to any previous state in seconds

Centralized vs Distributed link

In Git, every developer has the entire repository history locally. You commit offline, push when ready.

Core Concepts link

  Working Directory  →  Staging Area  →  Local Repository  →  Remote Repository
   (your files)        (git add)        (git commit)         (git push)
  

How Git Tracks Changes link

Git stores content as snapshots, not diffs. Each commit references a tree of files with SHA-1 hashes:

  commit a1b2c3d (HEAD -> main)
Author: Alice <[email protected]>
Date:   Thu Jun 13 2024

    Add user authentication

commit e4f5g6h
    Initial project setup
  

Every commit is immutable — changing history creates new commit hashes.

Your First Repository link

  mkdir my-project && cd my-project
git init
echo "# My Project" > README.md
git add README.md
git commit -m "Initial commit"
  

View history:

  git log --oneline
# a1b2c3d (HEAD -> main) Initial commit
  

Git vs Other Tools link

Git vs SVN: SVN uses a single central server; commits go directly to it. Git commits locally first — faster, works offline, flexible branching.

Git vs GitHub: Git is the tool; GitHub/GitLab/Bitbucket are hosting platforms. You can use Git entirely offline without any remote.

Git vs Dropbox/Google Drive: Cloud drives sync files but don’t understand code history, merges, or branches. Never use file sync for source code.

Typical Team Workflow link

  main (production-ready)
  ↑ merge PR
feature/login (Alice's branch)
feature/dashboard (Bob's branch)
  

1. Pull latest main
2. Create feature branch: git checkout -b feature/login
3. Commit changes locally
4. Push branch and open Pull Request
5. Code review, CI tests pass
6. Merge to main
7. Deploy

Git Configuration link

Set identity once globally:

  git config --global user.name "Simon Sheng"
git config --global user.email "[email protected]"
git config --global init.defaultBranch main
git config --global core.editor "code --wait"
  

Useful defaults:

  git config --global pull.rebase false   # merge on pull (default)
git config --global color.ui auto
git config --global alias.st status
git config --global alias.co checkout
git config --global alias.br branch
git config --global alias.lg "log --oneline --graph --all"
  

Common Git Hosting Platforms link

What Comes Next link

Continue to Git Basics for daily commands, then branching, advanced techniques, and team collaboration. Git proficiency is non-negotiable for any developer role.