The Referrer URL is the address of the webpage where the visitor came from. It is based on HTTP header "Referrer"

The reasons why a Referrer URL could be blank

• The website (where the offer creative is shown) is accessed from a HTTP Secure connection and the Tracking URL uses a non-secure connection.
• The Visitor has turned off the referrer option in his browser settings (some browsers support this).
• The Visitor used a Proxy server where it was configured to remove referrer headers.
• The Visitor typed/pasted Tracking URL directly to the browser's path field.
• The Visitor uses E-mail client software (not web based) and clicked the creative link within this program.
• The Visitor manually removed or replaced HTTP Referrer header.