0.2 — The Environment

Every scary thing, explained once:

Term	What It Is	Everyday Analogy
Terminal / Command Line / CLI	A text-based way to talk to your computer. Instead of clicking icons, you type instructions.	Texting your computer instead of tapping buttons. Same computer, different interface.
IDE (Integrated Development Environment)	A specialized text editor for working with code. VS Code is the most common.	Microsoft Word is for essays. VS Code is for software. It highlights errors, suggests completions, organizes files.
Git	A system that tracks every change you make to files, so you can undo anything and see full history.	Google Docs version history, but for your entire project — every file, every change, with labels you write.
GitHub	A website where people store and share Git-tracked projects. Also where teams collaborate.	Google Drive for code projects, with built-in tools for teamwork.
Repository (Repo)	A project folder tracked by Git.	A filing cabinet for one project where every change is recorded.
File extensions	Letters after the dot in a filename that tell the computer what type of file it is.	Like .jpg = photo and .mp3 = music — .json = data, .md = text, .py = Python code.

Key File Types

Extension	Full Name	What It’s For	Analogy
.md	Markdown	Formatted text. Documentation, notes, README files.	A text file with simple formatting codes — **bold** instead of clicking a B button.
.json	JavaScript Object Notation	Structured data. Config, settings, data exchange.	A fill-in-the-blank form your computer can read: "name": "CJ" — label left, value right.
.yaml / .yml	YAML Ain’t Markup Language	Same job as JSON, more human-readable. Config files.	Same form as JSON with less punctuation — easier on the eyes.
.py	Python	Code in the Python language.	The most common language AI tools are built in. You don’t need to write it — you need to recognize it.
.js / .ts	JavaScript / TypeScript	Code for web applications.	The language websites speak. TypeScript = JavaScript with stricter rules.
.env	Environment Variables	Secret settings (passwords, API keys). Never shared publicly.	Your project’s private diary — passwords and keys that never leave your machine.

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Next: 0.3 — How Software Works | Phase overview: Phase 0