With this feature turned on in your account Blueshift will automatically append the blueshift profile id (bsft_uid - unique identifier for each profile in Blueshift) to each link sent from a campaign. This allows Blueshift to identify a customer via their profile id instead of the cookie or any other identifier. This enables for more accurate profile matching.

Example:

A link to an article is sent to customer via a Blueshift campaign. With this feature turned on the link will look something like https://www.yourwebsite.com?bsft_uid=5a965ee6-0b4c-434c-8d44-2cca857d6a94 when the customer clicks on it. If on this web page you are running the Blueshift tracking script and/or sending a custom event over to Blueshift, the pageload/custom event will automatically include the blueshift profile id and will record it under that profile.