A page is rarely a single file. Scripts, stylesheets, images and frames come from somewhere, and each origin is a party that sees the visitor's IP address, one more connection to open, and — for scripts and stylesheets — code that runs with all the rights of the page. This check reads the markup once and sorts what it finds by origin, protocol and integrity.
From this server: exactly one request for the page, capped at 1.5 MB. None of the subresources are fetched. No cookies are sent, no scripts are executed, nothing is stored beyond the rate counter.
Limits worth knowing: only what stands in the served HTML is seen. What a script loads at runtime — the usual case for tag managers and consent tools — stays invisible, and so does anything inside a frame. Two hosts count as the same party when their registrable name matches, so a CDN subdomain of the same domain is not counted as third party.