GlossaryAnalytics and search
GA4 property
The container in Google Analytics 4 that holds a set of data streams and the configuration applied to them.
The trap
What makes it wrong.
Data retention is a property setting with a short default, and it applies to the event-level data behind custom explorations, not to the standard aggregated reports. A question that needs event-level history often cannot be answered at all beyond the retention horizon, and the interface answers with an empty result rather than an explanation.
In detail.
A property is the unit of reporting, of retention settings and of access. Several sites and apps can feed one property through separate data streams, which is what makes cross-platform reporting possible and also what makes a property's numbers depend on which streams are attached.
The property identifier, not the account, is what every reporting call takes.