Here are some details on the cookies and data used.
Data Used: Name, email address. This helps the blog make sure that emails go out to the right people.
Activity Tracked: IP address, which links are clicked in an email.
Data Used: If Akismet is enabled on the site, the contact form submission data — IP address, user agent, name, email address, website, and message — is submitted to the Akismet service (also owned by Automattic) for the sole purpose of spam checking. The actual submission data is stored in the database of the site on which it was submitted and is emailed directly to the owner of the form (i.e. the site author who published the page on which the contact form resides). This email will include the submitter’s IP address, timestamp, name, email address, website, and message.
Data Synced (?): Post and post meta data associated with a user’s contact form submission. If Akismet is enabled on the site, the IP address and user agent originally submitted with the comment are synced, as well, as they are stored in post meta.
This feature is only available to sites on the Premium and Professional plans.
Data Used: Please refer to the appropriate Google Analytics documentation for the specific type of data it collects. For sites running WooCommerce (also owned by Automattic) and this feature simultaneously and having all purchase tracking explicitly enabled, purchase events will send Google Analytics the following information: order number, product id and name, product category, total cost, and quantity of items purchased. Google Analytics does offer IP anonymization, which can be enabled by the site owner.
Activity Tracked: This feature sends page view events (and potentially video play events) over to Google Analytics for consumption. For sites running WooCommerce-powered stores, some additional events are also sent to Google Analytics: shopping cart additions and removals, product listing views and clicks, product detail views, and purchases. Tracking for each specific WooCommerce event needs to be enabled by the site owner.
Data Used: In order to process a post like action, the following information is used: IP address, WordPress.com user ID, WordPress.com username, WordPress.com-connected site ID (on which the post was liked), post ID (of the post that was liked), user agent, timestamp of event, browser language, country code.
Activity Tracked: Post likes.
Data Used: A visitor’s preference on viewing the mobile version of a site.
Activity Tracked: A cookie (akm_mobile) is stored for 3.5 days to remember whether or not a visitor of the site wishes to view its mobile version. Learn more about this cookie.
This feature is only available to sites on the Professional plan.
Data Used: Any of the visitor-chosen search filters and query data in order to process a search request on the WordPress.com servers.
Data Used: IP address, WordPress.com user ID (if logged in), WordPress.com username (if logged in), user agent, visiting URL, referring URL, timestamp of event, browser language, country code. Important: The site owner does not have access to any of this information via this feature. For example, a site owner can see that a specific post has 285 views, but he/she cannot see which specific users/accounts viewed that post. Stats logs — containing visitor IP addresses and WordPress.com usernames (if available) — are retained by Automattic for 28 days and are used for the sole purpose of powering this feature.