The referrer is, generally speaking, the last place the user visited before they landed on your webpage. If available, this information will be retrieved by our code.
However, there are some situations where this data may not be passed along with the conversion.
The referrer field may appear empty/unknown if the user:
entered the site URL in browser address bar.
visited the site by a browser-maintained bookmark.
visited the site as first page in a new window or tab.
clicked a link in an external application (such as email or a messaging service).
switched from a HTTPS URL to a HTTP URL.
switched from a HTTPS URL to a different HTTPS URL.
has security software installed (such as an antivirus or firewall, etc.) which strips the referrer from all requests.
is behind a proxy which strips the referrer from all requests.
has explicitly added a
"no referrer"keyword to the link that would prevent outbound links from sending a referrer to the destination site (your landing page).