Czym jest Session?

A session (or visit) groups everything one visitor does on your site in a single sitting: the pageviews, clicks, and events between arriving and leaving. Most tools end a session after a period of inactivity, commonly 30 minutes, so a visitor who returns in the afternoon starts a new session.

Sessions sit between pageviews and visitors in granularity. One person can generate many sessions, and one session can contain many pageviews. Session counts are the natural denominator for behavioral metrics: bounce rate, pages per session, and session duration are all per-session numbers. Watch out for tools that reset sessions at midnight or when the traffic source changes mid-visit, since those rules quietly change your numbers.

Cookieless tools like Analyse group pageviews into sessions on the server with a short-lived token instead of a stored identifier, which keeps visit-level metrics intact without a consent banner, as explained in the cookieless analytics guide.