A session is defined as a group of interactions one user takes within a given time frame on your website.
For example a single session can contain multiple page views, events, social interactions, and E-Commerce transactions. A single user can open multiple sessions. Those sessions can occur on the same day, or over several days, weeks, or months. As soon as one session ends, there is then an opportunity to start a new session. There are two methods by which a session ends:
- Time-based expiration:
- After 30 minutes of inactivity
- At midnight
- Campaign change:
- If a user arrives via one campaign, leaves, and then comes back via a different campaign.
By default, a session lasts until there’s 30 minutes of inactivity, but you can adjust this limit so a session lasts from a few seconds to several hours. See suggestions by Google in this link.