Privacy policy.
The short version
Advertising right now
/ads.txt file. Neither runs any code or sets any cookie.Every outside service
When: Every page. Vercel hosts the site and serves every page from our own domain.
Why: Someone has to serve the pages.
What it collects: Like any web host, Vercel receives the standard request details your browser sends (IP address, browser type, the page asked for) in order to deliver the page.
When: Every page, once analytics is switched on in our Vercel account. The script is served from our own domain.
Why: To count page views and see which pages are useful.
What it collects: Per Vercel’s documentation: no cookies; visitors are counted by a hash of the incoming request that is discarded after 24 hours; each page view records the time, the page, the referring site, filtered query parameters, rough location (country, region, city), operating system, browser and device type. We also send a few named events with no personal details: a tip-jar click, a book-link click, a PDF download, and an email signup (which list, not the address).
When: Only when you type an email address into a signup form and submit it.
Why: To store the address so we can tell you when the thing you signed up for ships.
What it collects: Your email address, which form you used (posters, embed or general), and the time you signed up. Your browser sends it to our own server, which writes it to an Upstash Redis database.
When: Only while advertising is switched on for the site (the privacy page says which state it is in). When it is on, Google’s ad code loads on some pages — never on classroom pages.
Why: Display ads would help pay for the site.
What it collects: Google’s ad code can set cookies (for example on doubleclick.net) and use them to choose and measure ads. Google describes this in its own policy.
When: Not used. The code can load it, but it is not configured on the live site.
Why: An alternative page-view counter we may use instead of Vercel’s.
What it collects: None today.
When: Only if you click the tip-jar link. The tip jar is a plain link; no Ko-fi code runs on our pages.
Why: Ko-fi handles tips so we never touch card details.
What it collects: Whatever you give Ko-fi on its own site, under its own policy. We never see card numbers.
When: Only if you click a book link. Book links are plain links with no tracking tag.
Why: Suggested reading for each era.
What it collects: None from us. We earn nothing from these links.