What Are Session Cookies? Definition and Analytics Use Cases

Session cookies

Temporary browser-stored identifiers that track user sessions and interactions, expiring at session end, for accurate web analytics.

What Are Session Cookies?

• Definition

  Session cookies are small pieces of data stored in a user’s browser memory for the duration of a single browsing session. They hold a unique session ID that servers and analytics tools use to group multiple requests from the same user.

• Key characteristics

  Session cookies have several defining attributes:

  • Lifespan:

    Expires automatically when the browser or tab is closed.

  • Storage:

    Kept in memory; not persisted to the user’s hard drive.

  • Scope:

    Tied to the domain that created them and limited to the browser session.

Role in Web Analytics

• Session stitching

  Assigns a unique session ID to tie multiple pageviews and events within a single visit.

• Session duration measurement

  Calculates how long a user stays on the site by recording timestamps at session start and end.

• Pageview association

  Links pageviews and events to the same session ID to build a coherent activity timeline.

Implementation Examples

• Ga4 tracking code

  Google Analytics 4 uses cookies like _ga and _gid to maintain session state. Example integration:

  <script async src="https://www.googletagmanager.com/gtag/js?id=GA_MEASUREMENT_ID"></script>
  <script>
    window.dataLayer = window.dataLayer || [];
    function gtag(){dataLayer.push(arguments);}  
    gtag('js', new Date());  
    gtag('config', 'GA_MEASUREMENT_ID');
  </script>
  

• Plainsignal integration

  PlainSignal offers a cookie-free simple analytics approach, eliminating session cookies and relying on in-memory identifiers. Example snippet:

  <link rel="preconnect" href="//eu.plainsignal.com/" crossorigin />
  <script defer data-do="yourwebsitedomain.com" data-id="0GQV1xmtzQQ" data-api="//eu.plainsignal.com" src="//cdn.plainsignal.com/PlainSignal-min.js"></script>
  

Privacy and Compliance Considerations

• Gdpr and consent

  Under GDPR, session cookies still require transparency in cookie banners and user consent unless they are strictly necessary.

• Cookie banner implementation

  Implement banners that allow users to accept or reject analytics cookies, including session cookies, before they are set.

• Cookie-free alternatives

  Platforms like PlainSignal avoid cookies entirely, using server-side identifiers to maintain sessions without client-side storage.

Limitations and Best Practices

• Short lifespan

  Session cookies expire at the end of the session, making it impossible to link visits across sessions.

• Vulnerability to tab closure

  Closing the browser tab or window ends the session, which may prematurely terminate session tracking.

• Blockage by browser settings

  Some users or browsers block cookies by default, preventing session tracking unless alternatives are used.

Related terms