Files, folders, and where stuff lives

Everything on your computer is either a file or a folder. That includes your photos, your music, the apps you've installed, and — importantly — the code Claude Code will eventually be writing for you. Once this idea clicks, half of what computers do stops feeling mysterious.

A file is a labelled box of bytes

A file is a single collection of data with a name on it. The name has two parts: the actual name (vacation) and an extension (.jpg) that tells the computer what kind of data is inside. So vacation.jpg is a photo, resume.pdf is a PDF document, song.mp3 is audio, and notes.txt is plain text.

Inside that box is just a long string of 1s and 0s. The extension is the computer's hint about how to interpret those 1s and 0s — as an image, as text, as a song. Strip away the extension and the bytes are still there, but now the computer doesn't know what to do with them.

A folder is a labelled box that holds other boxes

A folder (also called a directory — same thing, different word) is a container. It can hold files, and it can hold other folders, which can hold more files and more folders, all the way down. This is called a tree, because if you drew it out it would look like a tree with branches.

Here's a typical chunk of someone's computer:

Users/
└── harvey/
    ├── Documents/
    │   ├── taxes-2024.pdf
    │   └── resume.docx
    ├── Pictures/
    │   ├── vacation/
    │   │   ├── beach.jpg
    │   │   └── sunset.jpg
    │   └── profile.jpg
    └── Projects/
        └── my-website/
            ├── index.html
            └── style.css

Each /means "go into this folder." The full location of beach.jpg is Users/harvey/Pictures/vacation/beach.jpg. That string is called a path, and paths are how the computer (and Claude Code) refers to specific files.

The home folder

Every user on a computer has a home folder. That's where your personal stuff goes — Documents, Pictures, Downloads, and so on. On Mac and Linux it's usually /Users/yourname or /home/yourname. On Windows it's C:\Users\yourname.

The shorthand ~(tilde) means "my home folder." If a tutorial tells you to put something in ~/projects/zerotoclaude, that means inside your home folder, in a sub-folder called projects, in another sub-folder called zerotoclaude.

Hidden files

Some files and folders start with a dot, like .gitignore or .claude. Those are hiddenby default — your file browser won't show them. They're usually configuration files that apps create to remember settings.

You'll meet plenty of these in Claude Code land — for example, Claude Code keeps its settings in a hidden folder called .claudeinside your project. It's not hiding anything from you; it's just out of the way so your project folder doesn't look cluttered.

What is a "project folder"?

When developers work on something — a website, an app, a script — they put everything related to that work in one folder, called a project folder. The website's code, its images, its configuration, all live inside one parent folder. When you run Claude Code, you point it at one of these project folders, and it treats that folder as the world it's allowed to look at.

This is why we always start by "opening" a folder. The folder is the boundary of the project. Nothing outside that folder is part of the work.