What explorations are

Explore (left nav) is GA4's ad-hoc analysis workspace. Where standard reports read from pre-aggregated tables, explorations query the raw event data on the fly. That buys you things reports cannot do:

• any combination of dimensions and metrics, including nested rows and pivots,
• segments (subsets of users, sessions or events) and sequence conditions,
• techniques beyond tables: funnels, paths, cohorts, segment overlap, a per-user timeline, lifetime values,
• tables with up to 500 rows and export to Sheets, CSV or PDF.

The trade-offs are just as important:

• Retention window: explorations can only see events within your data retention setting (2 or 14 months, 50 for 360). A standard report happily shows three years; an exploration over the same range silently returns nothing older than the window.
• Sampling: when a query covers more than 10 million events (1 billion for 360), GA4 analyses a sample and extrapolates. An icon at the top right of each tab shows a green tick for unsampled data or a warning with the sampling percentage.
• Thresholding applies as in reports, and data freshness is the same (typically a few hours to a day).
• Explorations are personal: created by you, visible only to you unless shared, and sharing is read-only. Each user can own up to 200 explorations per property, and a property holds up to 500 shared ones.

Seven techniques exist: Free form, Funnel exploration, Path exploration, Segment overlap, User explorer, Cohort exploration and User lifetime. A single exploration can hold up to ten tabs mixing them, all sharing the same variables.

Rule of thumb: Reports for monitoring and known KPIs; Explore for a question you have not answered before.