Cookie policy
Last updated: October 1, 2026
Your choice:
What cookies are
Cookies are small files a website saves in your browser. Websites can also save information in your browser's own storage (localStorage). This page lists everything this site saves, and what's optional.
Always on: needed for the site to work
These are saved in your browser's storage. They never leave your device and we can't see them. Because the site needs them to do what you ask, they don't need your consent.
| Name | What it's for | How long |
|---|---|---|
cht-done | Which lessons and final challenges you've finished | Until you clear it |
cht-distro | Whether to show Rocky, Ubuntu or both | Until you clear it |
cht-theme | Light, dark or automatic colours | Until you clear it |
cht-recipes | Your ticks on the recipes checklists | Until you clear it |
| Offline copies (browser cache) | The pages and files you've opened, so lessons and the practice terminal still work without internet. Pages are always fetched fresh when you're online. | Until your browser clears its cache, or you clear this site's data |
cht-beta-hidden | That you closed the “Public beta” message, so it stays closed | Until you clear it |
cht-fb | Which pages you answered “Was this helpful?” on, so the buttons show your answer | Until you clear it |
cht-consent | Your cookie choice, so we don't ask again | Until you clear it |
When optional accounts arrive, signing in will use a cookie to keep you logged in. That cookie will be strictly necessary too, and listed here.
Optional: analytics
Only if you click Accept:
| Name | What it's for | How long |
|---|---|---|
cht-aid (browser storage) | A random number, made up by your browser. It's sent with our own anonymous page measurements so we can link your visits on different days: whether you come back, how far you get through a path (from your progress saved in this browser), and how long a path takes. It's never linked to your name, email or IP address, and our server only keeps a scrambled version of it. | Until you click Reject or clear this site's data. What we hold under it is deleted when you click Reject, or 400 days after your last visit. |
Later we may also use Google Analytics to learn which lessons people use and where they get stuck. It isn't switched on yet. When it is, it will only load if you clicked Accept. If you click Reject, or your browser sends a Global Privacy Control signal, it never loads. We'll list its cookies here (their names, what they do and how long they last) before it goes live.
Without your Accept, our own visit counts and reading-time measurement don't use cookies or browser storage at all, and they reset every day. The privacy policy explains how they work.
Changing your mind
Use Change cookie settings above, or Cookie settings at the bottom of every page. If you switch analytics off after allowing it, we ask our server to delete what it kept under your random number, remove the number from your browser, and reload the page. You can also clear this site's cookies and storage in your browser's settings. That also clears your lesson progress.