Cookies Used by Piwik PRO
Piwik PRO stores a lot of data inside of cookies, It creates first-party cookies in the domain of your website. Here is the list of the cookies and their purpose:
_pk_ref – These cookies hold information about referrers of the visitor, its default lifetime is 6 months.
_pk_cvar – These are only used when you decide to set a custom variable within visitor scope
_pk_id – This keeps visitor ID value used by Piwik to recognize returning visitors, by default the lifetime of the cookie is 1 year
_pk_ses – Session cookies are responsible for keeping the session active for 30 minutes after last tracked action, when they expire the visit is considered as ended, the time can be altered.
_pk_hsr – these are not Piwik core cookie, they are created by a third party software and are not used by Piwik PRO
piwik_ignore – This cookie is set in the browser of visitors who opted-out from being tracked by Piwik PRO. It tells the tracker to ignore the visitor and not send any data about him to the Piwik PRO server.
_pk_uid – if for some reason you’ll decide to use third-party cookies in your Piwik PRO account the cookie used for recognizing the UserID name will start with _pk_uid. This can later be used to track same visitors across multiple domains. Its default lifetime is 1 year