Distinct ID

A distinct ID is the single identifier an event analytics tool uses as the primary key of a user profile, so all events carrying the same value belong to one person.

Before login the distinct ID is the anonymous value the library generated on the device; after an identify call the tool maps it to the account identifier and both resolve to one profile. The name is not stable across vendors: the term comes from Mixpanel, Amplitude splits the same role between an Amplitude ID and a user ID, and warehouse models usually call it a canonical ID. The frequent mistake is overwriting the distinct ID directly instead of going through the tool's identity interface, which splits one person into two profiles because events already written keep the old value.