Git Fundamentals

Git Fundamentals

Git is a distributed version control system. Every developer has a full copy of the repository history, and changes are tracked as a series of snapshots (commits).

Key Concepts

Term	Description
Repository	The .git directory that stores all history and metadata
Working tree	The files you see and edit
Index / Staging area	Changes prepared for the next commit
Commit	A snapshot of staged changes with metadata (author, timestamp, message)
Branch	A lightweight pointer to a commit
HEAD	A pointer to the current branch (or commit in detached HEAD state)
Remote	A version of the repository hosted elsewhere (GitHub, GitLab, etc.)

Configuration

git config --global user.name "Your Name"
git config --global user.email "you@example.com"
git config --global core.editor "code --wait"   # VS Code as editor
git config --global init.defaultBranch main

# View all config
git config --list

Starting a Repository

# New repo
git init
git init my-project   # creates directory

# Clone existing repo
git clone https://github.com/user/repo.git
git clone https://github.com/user/repo.git my-folder   # custom directory name

The Three States

Files move through three states:

Untracked / Modified → Staged → Committed
         git add ↑         git commit ↑

# Check current state
git status
git status -s    # short format

# Stage specific files
git add file.txt
git add src/         # entire directory
git add .            # everything in working directory

# Unstage
git restore --staged file.txt

# Commit staged changes
git commit -m "Add user authentication"

# Stage and commit tracked files in one step
git commit -am "Fix typo in README"

Viewing History

git log
git log --oneline              # compact view
git log --oneline --graph      # with branch graph
git log --oneline -10          # last 10 commits
git log --author="Alice"
git log --since="2 weeks ago"
git log -- path/to/file        # commits affecting a specific file
git show abc1234               # show a specific commit

Branches

# Create and switch
git branch feature/login
git switch feature/login
git switch -c feature/login    # create + switch in one step

# List branches
git branch          # local
git branch -r       # remote
git branch -a       # all

# Delete
git branch -d feature/login    # safe delete (warns if unmerged)
git branch -D feature/login    # force delete

# Rename
git branch -m old-name new-name

Merging

# Merge feature branch into main
git switch main
git merge feature/login

# Merge with a merge commit (no fast-forward)
git merge --no-ff feature/login

# Abort a merge in progress
git merge --abort

Working with Remotes

# List remotes
git remote -v

# Add a remote
git remote add origin https://github.com/user/repo.git

# Push
git push origin main
git push -u origin main    # set upstream (then use just `git push`)
git push --all             # push all branches

# Pull (fetch + merge)
git pull

# Fetch (download without merging)
git fetch origin

# Delete remote branch
git push origin --delete feature/old-branch

Viewing Differences

# Changes not yet staged
git diff

# Staged changes (about to be committed)
git diff --staged
git diff --cached   # same thing

# Between two commits
git diff abc1234 def5678

# Between branches
git diff main feature/new

.gitignore

# Dependencies
node_modules/
.venv/

# Build output
dist/
build/
*.pyc

# Secrets
.env
.env.local
*.pem
secrets.json

# IDE
.vscode/
.idea/
*.swp

Generate recommended .gitignore files at gitignore.io.