Media & Publishing / Audience

Unique Visitors UV (aka unique users, uniques, monthly unique visitors / MUV, deduplicated audience)

How many distinct people visited, in principle a person counted once no matter how often they came back.

The fork, why two teams get different numbers

"Distinct" is measured three incompatible ways.

In the Metric Library

The full fork, both definitions worked all the way through
The trap that makes the number lie, on a real export
Every formula variant, spelled out
The reconciliation anchor, what to tie it to and when to refuse

Reference: MRC Unique Audience / dedup guidelines (reference); IAB audience-measurement convention (reference); Comscore/Nielsen panel methodology (reference)