User ID views
A special type of reporting view that only includes data about the subset of traffic that has a user ID assigned.
User ID views include a set of Cross Device reports, which aren’t available in other reporting views. The Cross Device reports give you the tools you need to analyze how users engage with your content on different devices over the course of multiple sessions. All other standard reports and tools are also available in User ID views.
User ID views do not include all of your data. To analyze all of your data, use a different type of reporting view.
User ID view are only available to Universal Analytics properties in which the User ID is enabled. You must also create User ID views. They do not exist by default in your account.