What the referrer contains
It may include the full address of the previous page, including paths that reveal what you were reading.
Modern defaults
Most browsers now send only the origin to other sites by default, reducing detail.
Site policies
Sites can set stricter referrer policies. Careful information sites often use 'strict-origin-when-cross-origin'.
Practical impact
When moving from a Vortex Market guide to another site, the destination usually learns only the site name, not the specific page.