Croct says anonymous and identified profiles never associate, what does that mean?
Reading through the identity docs I found two statements that seem to pull in opposite directions. One says anonymous and identified profiles never associate with each other for sync. Another says identity resolution can link a returning user back to their profile.
I want to understand how both are true at once, and what it means for my segmentation once visitors start logging in. I tend to reason these things through carefully before I minimise what we store.
1 answer
Both are true because they describe two different mechanisms.
The "never associate for sync" statement is about profile syncing: an anonymous profile and an identified profile are not silently kept in lockstep, one does not mirror the other in the background.
Identity resolution is the separate, explicit mechanism that links profiles. It matches on contact attributes like email or phone, running up to 5 rounds of matching. On a conflict, the most recent value wins per attribute, while set attributes such as interests merge rather than overwrite.
For segmentation, the practical upshot is that linking only happens through those matching rules, on the attributes you actually collect. If you never store a contact attribute, there is nothing for resolution to match on, which is often fine. See personalizing anonymous visitors with no PII for how far you can get without any of that.