A session is a group of user interactions with a website that occur within a defined time frame, typically ending after a period of inactivity (commonly 30 minutes) or at midnight, depending on the analytics platform's rules.
Session boundaries are a configuration choice, not a fixed law — most tools default to a 30-minute inactivity timeout, but some also cut a session at midnight or when a visitor arrives via a new campaign link mid-visit. The same real-world visit can be counted as one session in one tool and two in another purely due to differing timeout rules, a common source of numbers not matching between platforms.
A visitor browses a site for 10 minutes, leaves the tab open for a 45-minute lunch break, then returns and clicks a link — most tools count that as two separate sessions because the inactivity gap exceeded the timeout window.
Most analytics platforms default to a 30-minute inactivity window, after which further activity starts a new session, though some tools allow this timeout to be configured.
Yes — every time a visitor returns after the inactivity timeout has passed, or crosses a session-ending boundary like midnight, a new session is recorded even though it's the same person.
They're generally the same concept under different names — most analytics tools use 'session' and 'visit' interchangeably to describe one continuous period of activity by a single visitor.