What Are Blocked Referrers?

Answer

Blocked referrers occur when referrer data is not passed due to browser or security policies, and are counted as direct traffic.

Definition

Whether a referrer is passed along in the browser is determined by the referrer policy on the external referring site. Referrals that are blocked by a referral policy are included in the Direct traffic statistics in Siteimprove. When a visitor navigates to a non-secure (HTTP) site from a link on a secure (HTTPS) site, it is registered as a direct traffic referrer. This is because the secure site will not pass referrer information to the non-secure site. Read more on Referrer-Policy best practices (Google dev site).