Paths: how to name any file

1. The promise

You'll be able to write the full path of any file on your machine, tell an absolute path from a relative one, and know why / and \ are different and which one your system uses.

2. The mental model

A path is the instructions to walk through the tree to a specific file.

• An absolute path starts at the root. Like giving directions from the central station: "from the station, take the train to Brunswick, walk three blocks east, second door."
• A relative path starts wherever you happen to be right now. Like giving directions from the coffee shop you're already at: "two doors down, on the left."

The vocabulary, said properly:

• A path is a string that names a file by giving the route through the folder tree.
• An absolute path starts at the root (/ or C:\).
• A relative path is interpreted from a current location.
• The parent folder is the folder one level up. Written as .. (two dots).
• The current folder is the folder you're in. Written as . (one dot).
• The home shortcut ~ (tilde) means your user's home folder. macOS and Linux always understand it; modern Windows PowerShell does too.
• The path separator is the character between folder names. / on macOS and Linux. \ on Windows.

(DIAGRAM: anatomy of a path — annotated SVG — /Users/yourname/Documents/notes.txt split into labelled segments: root, user-folder, subfolder, filename)

(DIAGRAM: absolute vs relative — annotated SVG — same target file, two arrows: one from root labelled "absolute /Users/yourname/Documents/notes.txt", one from a "current location" labelled "relative ./Documents/notes.txt")

3. You do it, with me

We're going to read paths off your own machine and write three down.

Step 1. Pick any file in your Documents folder. A .docx, a .pdf, the hello.txt you made in unit 0.4. Anything.

Step 2. Copy its full path.

• macOS: right-click the file -> hold Option -> the menu item changes from "Copy" to "Copy filename as Pathname". Click it.

(SCREENSHOT: macOS right-click menu with Option held — showing "Copy notes.txt as Pathname" — highlighted)

• Windows: hold Shift, right-click the file -> "Copy as path".

(SCREENSHOT: Windows File Explorer right-click menu with Shift held — showing "Copy as path" — highlighted)

Step 3. Paste it into TextEdit or Notepad. You'll see something like:

• macOS: /Users/yourname/Documents/notes.txt
• Windows: "C:\Users\yourname\Documents\notes.txt" (Windows adds quotes)

(SCREENSHOT: macOS Get Info for notes.txt — full window — "Where" field highlighted)

(SCREENSHOT: macOS Finder address bar with full path visible (after View -> Show Path Bar) — full window)

(SCREENSHOT: Windows File Explorer address bar with full path visible — full window — the address bar highlighted)

Step 4. Walk through the path left to right. Take /Users/yourname/Documents/notes.txt apart:

• / — the root.
• Users — a folder inside the root.
• yourname — your home folder, inside Users.
• Documents — a folder inside your home.
• notes.txt — the file itself.

Read it out loud. "Root, Users, your name, Documents, notes-dot-txt." Do this once and the shape sticks.

Step 5. Do steps 2 to 4 for two more files. Pick one in Downloads and one on the Desktop. Paste all three paths into the same TextEdit or Notepad window.

(SCREENSHOT: a text file containing the three pasted paths — TextEdit or Notepad — full window)

Step 6. Try the dots. From the path /Users/yourname/Documents/notes.txt:

• .. from Documents means /Users/yourname/.
• ../Downloads/ from Documents means /Users/yourname/Downloads/. Up one level, then into Downloads.
• . means Documents itself.

You won't type these in the file manager. You'll type them constantly in the terminal in Ch 2 and in code from Ch 4 onwards.

Step 7. The home shortcut. Instead of /Users/yourname/Documents, you can write ~/Documents. The OS expands ~ to your home folder. This works on macOS, on Linux, and in modern Windows PowerShell.

Step 8. The separator difference. macOS and Linux use /. Windows uses \. When you write JavaScript later (Ch 6), URLs and many APIs use / even on Windows. Don't fight it — prefer / in code, even on a Windows machine, except when you're talking to Windows-only tools.

4. What you should be seeing

A text file with three absolute paths from your machine, each starting at / or C:\. You can read each one out loud and name each segment.

You can also write the relative path from Documents to a file in Downloads: ../Downloads/filename. Up one, into Downloads, file name.

5. Common stumbles

• You wrote the path with the wrong separator. Backslashes on macOS, forward slashes on Windows when talking to a Windows-only tool. The fix is always to copy the path from the file manager, never type it from memory.
• You forgot the leading / or C:\ and the path is relative when you meant absolute. Absolute paths always start at the root. If your path starts with a folder name, it's relative.
• Spaces in folder names bite. My Documents has a space. In code or in the terminal, that space looks like the end of one argument and the start of another. The fix is to wrap the whole path in quotes: "My Documents". We come back to this in Ch 2.
• The terminal's "current folder" feels mysterious. It isn't. It's the same idea as "the folder File Explorer is currently showing" — just text instead of a window. Every relative path is read from there.

6. You should know