What is the `personalization_id` Cookie?

Set by Twitter / X (X Corp.). Expires after 2 years.

Purpose

Used by Twitter/X to track visitors and serve personalised advertising, set when a page embeds tweets, timelines, or the Twitter Pixel.

Set in a third-party context by embedded Twitter/X widgets. Requires marketing consent.

Marketing cookies are used to track visitors across websites to display relevant advertisements. Consent is required under GDPR.

Under GDPR and the ePrivacy Directive, the personalization_id cookie requires explicit user consent before it can be set. This means:

The cookie must not be set when a user first visits your site — not even for a fraction of a second
A consent banner must be displayed, and the user must actively accept analytics/marketing cookies
If the user rejects or ignores the banner, this cookie must remain blocked
The cookie must be listed in your cookie policy with its name, purpose, and retention period
Users must be able to withdraw consent at any time, which must also remove or invalidate this cookie

Block it by default — configure your Consent Management Platform (CMP) or tag manager to prevent Twitter / X from loading until the user accepts marketing cookies.
Include it in your consent categories — map it to the "Marketing / Advertising" category in your CMP configuration.
List it in your cookie policy — document the cookie name, purpose, provider (X Corp.), and expiry (2 years).
Sign a DPA — ensure you have a Data Processing Agreement with X Corp. covering their use of data collected via this cookie.
Verify it works — in an incognito browser, reject cookies and confirm personalization_id is not set.

Cookie	Category	Duration
guest_id	Marketing / Advertising	2 years

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