What Is a Session in Web Analytics? (The 30-Minute Rule Explained)

Short answer: a session is a group of interactions one visitor has with your website in a single visit. By convention it ends after 30 minutes without activity. One person can have many sessions, and one session can contain many pageviews.

Table of Contents

1. Session, User, Pageview
2. When a Session Starts and Ends
3. Why 30 Minutes?
4. Cases That Confuse People
5. Why the Definition Matters
6. How DeepSync Defines a Session
7. Key Takeaways

Session, User, Pageview

Someone who visits on Monday, Wednesday, and Friday and looks at four pages each time is one visitor, three sessions, twelve pageviews.

When a Session Starts and Ends

A session starts when a visitor arrives with no session currently active.

A session ends when one of these happens, depending on the tool:

• Inactivity. No interaction for 30 minutes.
• Tab or browser closed. Some tools end the session immediately.
• Midnight. Some tools start a new session when the date changes.
• New campaign source. Some tools start a new session if the visitor returns through a different ad or link.

Only the first rule is close to universal. The other three are where tools differ, and they are a major reason analytics numbers never match.

Why 30 Minutes?

It is a convention, not a law of nature. Thirty minutes is long enough to cover reading a long article or stepping away briefly, and short enough that a return after lunch counts as a new visit. Some tools let you change it. For most sites the default is reasonable.

Cases That Confuse People

The long lunch

A visitor opens your pricing page, leaves the tab open for an hour, then comes back and signs up. That is two sessions. The signup is credited to the second.

The payment detour

A shopper is sent to a bank or payment page and returns four minutes later. It is still one session by the inactivity rule, though some tools may treat the returning referrer as a new source.

Two tabs

Two tabs open at once in the same browser are normally one session.

Two devices

A phone and a laptop are two sessions and, unless the person is logged in and identified, two visitors.

Single-page apps

In an app that never reloads, route changes count as pageviews only if the tool tracks them. Otherwise the whole visit looks like one page.

Why the Definition Matters

• Conversion rate. It is conversions divided by sessions. Split one visit into two and the rate falls.
• Pricing. Many tools bill by session, so the definition affects what you pay.
• Bounce rate. A session cut short by a timeout can look like a bounce.
• Comparisons. Two tools with different rules will never agree exactly.

How DeepSync Defines a Session

In DeepSync, a session is one visit that ends after 30 minutes of inactivity or when the tab closes. It is what replay records and the unit your plan limit counts. A visitor is one person across many visits, identified by a persistent anonymous ID (core concepts).

Plan limits count sessions rather than pageviews or visitors because sessions are what cost storage (session limits). Client-side route changes in single-page apps are recorded as page views automatically, so a long visit in a React or Vue app is still one session with many pages.

Key Takeaways

• A session is one visit; a visitor can have many.
• Thirty minutes of inactivity is the common ending rule.
• Rules about midnight, tab close, and campaigns differ between tools.
• The definition affects conversion rate, bounce rate, and billing.

Conclusion

"Session" sounds obvious until two tools disagree. Knowing the rule your tool uses makes every other metric easier to read.

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