To track visitors, Piwik by default uses 1st party cookies, set on the domain of your website. Cookies created by Piwik start with: _pk_ref, _pk_cvar, _pk_id, _pk_ses.

When you exclude yourself from being tracked using the cookie method, Piwik will create a cookie “piwik_ignore” set on the domain of your Piwik server (which might be a third party cookie if Piwik is setup on a different URL from the website being tracked).

You can also Disable all first party cookies from being set — for example privacy reasons.

Piwik by default does not use third party cookies but you can enable a third party “_pk_uid” cookie it if you wish.