The article discusses a new feature in Firefox called Total Cookie Protection which aims to improve privacy by isolating tracking cookies to individual websites instead of allowing them to be shared across different sites. This new feature prevents third-party cookies that are used for advertising from being able to track a user's browsing activity across the entire web. The feature is enabled by default for all U.S. Firefox users and will be gradually rolled out to other countries and regions over time to help limit online cross-site tracking through third-party cookies.