After you deploy the visitor ID service, there are 5 ways a visitor can be identified in Analytics.
In many scenarios you might see 2 or 3 different IDs on a call, but Analytics will use the first ID present from that list as the official Experience Cloud ID. For example, if you are setting a custom visitor ID (included in the vid query parameter), that ID will be used before other IDs that might be present on that same hit. See Setting Analytics and Experience Cloud IDs for more information.
