Session

A session is a stretch of continuous user interaction with a website or app. It starts when the user opens a page or the app and ends after a set period of inactivity, which is 30 minutes by default in Google Analytics.

What is a session?

A session groups actions that happen close together in time into one visit. It is different from a user (which counts people or devices) and from an event or pageview (which counts individual actions). Someone who reads an article at 9:00, goes to a meeting and comes back at 9:45 creates two sessions under the default 30-minute setting.

Each tool draws the line between sessions with its own rules:

• GA4: a session starts when a user opens the app in the foreground, or views a page or screen while no session is active. A session expires after 30 minutes of inactivity and has no maximum length. The timeout can be adjusted. In apps, the inactivity timer starts when the app moves to the background, unless you send the extend_session parameter, which helps map or music apps (Google Analytics Help, About Analytics sessions, accessed October 2026).
• App Store Connect: Apple counts a session when the app is used for at least 2 seconds. An app that was running in the background and is opened again also counts as a new session. The data comes only from users who agreed to share analytics data (Apple, App Store Connect metrics, accessed October 2026).
• MMPs: each mobile measurement partner has its own rules.

What changed after Universal Analytics shut down

Standard Universal Analytics properties stopped processing data on July 1, 2023, and starting the week of July 1, 2024, users lost access to all UA data (Google Analytics Help, updated July 2025). Sessions are now measured with GA4 logic:

• The session_start event carries the session’s source information, such as gclid, UTM parameters and the referrer. Session attribution uses last click and ignores direct traffic: a visitor who arrives from Google organic search on day 1 and comes back directly on day 68 still has the later session recorded as google / organic.
• Session counts in reports are estimated with the HyperLogLog++ algorithm, so they differ slightly from BigQuery. Google’s own example shows 1,463 sessions in reports against 1,501 in BigQuery.
• Bounce rate has been redefined. An engaged session is one that lasts longer than 10 seconds, includes a key event, or has at least 2 page or screen views. Bounce rate is the percentage of sessions that meet none of these conditions (Google Analytics Help, Engagement rate and bounce rate, accessed October 2026).

Hypothetical example: reading session numbers

The landing page for an apartment project in Ho Chi Minh City gets 10,000 sessions from ads in a month, and 3,200 of them are engaged sessions. That works out to a 32% engagement rate and a 68% bounce rate. Organic search brings in 4,000 sessions, 2,000 of them engaged, for an engagement rate of 50%.

Do not conclude that the ads are performing badly. Visitors from ads often have not heard of the project before, while searchers already have intent. The next comparison is the lead submission rate per engaged session.

Session vs user vs ad click

Frequently asked questions

Why are there fewer sessions than Google Ads clicks?

Google Ads counts clicks and GA4 counts sessions. According to Google, a user may click and then close the browser before the tracking code loads, a redirect on the landing page may strip the gclid, or the browser may block data collection. Google Ads also filters out invalid clicks automatically, while GA4 still records those sessions (Google Ads Help, accessed October 2026).

Should you increase the session timeout?

You can, if users often read or watch video for long stretches without interacting, as on course pages. Write down the date of the change, because session counts before and after it cannot be compared directly.

Sessions feed into metrics such as retention rate and DAU. If you need to review how your landing pages are measured before raising the budget, see Adtek’s Lead Generation page or contact the team.