Unique Pageview
IntermediateA unique pageview is the number of sessions in which a page was viewed at least once, without counting repeat views of that same page inside the same session.
The de-duplication key is the combination of session and page: a visitor who returns to a product page three times in one session produces three pageviews and one unique pageview. There is a genuine tool collision here, because the metric comes from Universal Analytics and was removed in GA4, so a report migrated from the older version suddenly shows a larger number as the measure reverts to counting every view. The most damaging misreading is treating unique pageviews as the number of people who saw the page: one person visiting that page in five separate sessions produces five unique pageviews. The gap between pageviews and unique pageviews is itself a signal, and usually comes from reloads or back-button navigation.
How it is calculated
Unique pageviews = number of sessions in which that page was opened at least once
De-duplication happens inside a session, not across the reporting range, so a longer range produces a larger number because it contains more sessions. Summing the metric over all pages does not equal the site's total traffic, because one session can contain many different pages.