Privacy

This site has no accounts, and does not ask for your name or email address. We count visits so we can see which pages and figures are used and where the book needs work. We use two tools for that: Google Analytics and PostHog.

Both tools record the pages you view, your device info, and your approximate location (country and city). PostHog records clicks on links and controls. If you use the book with an AI assistant (such as ChatGPT or Claude), the page never sees what you say to the assistant, only the changes the assistant makes to the figure.

Google Analytics uses cookies so it can tell when the same browser comes back. PostHog does not use cookies, so it counts each page you open on its own and cannot recognize you from one page or visit to the next.

We use these numbers only to understand how the book is read and where to focus improvements and additions, and we do not sell them. Google and PostHog handle the data under their own policies. Most ad blockers stop both tools.

Questions about this page can go to respphys.book@gmail.com.

Last updated October 28, 2026.