Does identifying a user mean storing personal data?

Not necessarily. The user ID should be an internal, opaque value such as the account row ID in the product database. Sending an email address or phone number as the ID pushes personal data into the analytics store, which raises a privacy risk and also splits the user again whenever that value changes.

Identified User

Intermediate

Updated Jul 11, 2026 Shahin editorial 2 min read

PronunciationEN/aɪˈdentɪfaɪd ˈjuːzər/

An identified user is a visitor that carries a stable user ID supplied by the product, usually set at login, rather than only an anonymous browser identifier.

Before identification, events are stored against an anonymous browser identifier. When the product supplies its own user ID through an identify call, that ID becomes the join key and later events carry it, so one person can be followed across browsers and devices. Tools disagree on what counts as identified: some treat any profile holding an email address as identified, others only a profile that received an explicit identify call. The common error is reading the identified-user count as a login rate, because someone who never signs in on a second device stays two separate profiles until the identities are merged.

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