What are cookies?

Cookies are small text files placed by your browser on your device when you visit a website to store certain information. Using the stored information, a website can recognize that you have previously accessed and visited it using the browser on your end device.

How do we use cookies?

CERN uses cookies to arrange and display the website optimally in accordance with your preferences (such as login, language, font size and other display preferences) so that you do not have to keep re-entering preferences each time you visit the website.

Which cookies do we use?

Necessary Cookies

These cookies are necessary for the functioning of the website.




Used for

cerndrupal_prod_https End of session Used for load balancing to distribute incoming traffic across a backend servers.


1 year

Used to record which cookies the web user has consented to.

SimpleSAMLAuthToken, SimpleSAMLSessionID 8 hours validity tokens or until logged out Used, only when a web user logs in with a username and password, to distinguish authenticated sessions.
SSESS... End of session Used, only when a web user logs in with a username and password, to keep track of the current authenticated session.

Matomo Analytics

CERN uses Matomo Analytics to analyse traffic to the website and help improve website performance. Embedded videos from the CERN Document Server (CDS) also use Matomo Analytics to track viewing statistics.
Matomo Analytics data is stored at CERN.



Used for

_pk_id... 13 months Used to distinguish web users
_pk_ses... 30 minutes Used to keep track of the current session
session End of session Used by, only when there is an embedded CERN Document Server (CDS) video on a webpage, to track statistics and provide a better user experience e.g. replaying a video from where the user previously stopped watching.

For more details, see this Matomo webpage.

How to control cookies

You can control and/or delete cookies as you wish – for details, see You can delete all cookies that are already on your computer and you can set most browsers to prevent them from being placed. If you do this, however, you may have to manually adjust some preferences every time you visit a site and some services and functionalities may not work.

Further information

Read our full data privacy protection policy