A session is a group of events from one visitor that belong to one visit. Most of the numbers marketing cares about are session-level: landing page, traffic source, bounce, conversion rate, cost per visit.
A session is a rule, not a fact. Visitors don’t announce when a visit ends, so every tool decides it with an inactivity timeout and a set of splitting rules.
Why It Matters
If you don’t know how your sessions are built, you don’t really know what your session-level numbers mean. It’s also why two tools never report exactly the same session count.
In d8a.tech
Sessions are built on the backend and written to your warehouse as finished session_* columns.