A single, continuous period of activity by one visitor on a website, typically defined as ending after a set period of inactivity (commonly 30 minutes) or at midnight, after which any further activity counts as a new session.
Why it matters
Sessions is one of the most basic traffic metrics, but it's easy to misread if the underlying definition isn't understood — a single person can generate multiple sessions in one day if they leave and come back, so "sessions" doesn't equal "unique visitors."
In a sentence
"Traffic looked like it doubled, but a lot of that was the same visitors generating multiple sessions during a product launch, not genuinely new visitors."
Related terms
- Often confused with: Unique visitors (a session is one visit; a unique visitor is counted once regardless of how many separate sessions they generate over a given period).
- Synonyms: Visits.