Where does the demand data on this site come from?

From first-party search and server measurement across a portfolio of healthcare and technology properties, held in a private data warehouse.

The two independent streams are Google Search Console performance data, which shows which queries surfaced which pages, and server request logs, which show what actually reached the server, including classified search and AI crawlers.

Both have limits worth stating. A recorded impression does not prove a human typed the query, and a server request does not prove indexing, citation, or a reader. What the data does establish is which questions are being asked often enough, and specifically enough, to be worth covering. The full statement of method and limitations is on the methodology page.