Cookie Retention
A user lands on a page you own (for the first time) with a Dreamdata tracking script. The user is then assigned an anonymous ID stored as a first-party cookie in the user's browser with an expiration of 1 year. The expiration renews every time the user returns. The cookie is also replicated to local storage with no expiration date. The tracking script tracks across subdomains out of the box.
When that user arrives on another page later, we will re-use that locally stored anonymous ID if it is present, and those sessions will be visible as a single user inside Dreamdata. If the user is identified using an email in the browser, the email will act as the identifier across sessions, browsers, and devices.
If the user clears their cookies or some automated browser cookie-clean cycle has been in effect, that user will be assigned a new anonymous ID and will effectively be a separate anonymous user in our system. Suppose the unique anonymous ID is associated with an email at a later point. The activities will union based on the email associated with the same users and persist across sessions, browsers, and devices.
Dreamdata keeps all anonymous IDs in our database. We experience that most browsers (including Safari) use first-party cookies and only remove them when they expire. However, users can clear cookies, and browsers work differently depending on user settings.
Browser behavior might change in the future. Therefore it's recommended to ensure users are identified with email as often as possible or when it makes sense, as that removes the need for cookies to persist over extended periods. Identifying frequently ensures that cookies are less essential. It also provides that you can track users across devices.
3rd party cookies
Dreamdata does not use or benefit from 3rd party cookies. 3rd party cookies have shorter retention in some browsers (e.g., Safari) and will likely, over time, stop working or become even more restricted.
