Third-party cookies, also known as cross-site cookies, are cookies set by a website other than the one you are currently on. For example, cnn.com might have a Facebook like button on their site. The like button will set a cookie that can be read by Facebook. That would be considered a third-party (cross-site) cookie. Some advertisers use these types of cookies to track your visits to the various websites on which they advertise. This is called cross-site tracking.

When third-party cookies are disabled, it can stop some, but not all types of tracking. If you are concerned about tracking, see also:

• Enhanced Tracking Protection in Firefox for desktop
• Trackers and scripts Firefox blocks in Enhanced Tracking Protection

Disable third-party cookies

To block cross-site trackers or all third-party (cross-site) cookies:

1. In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button and select Settings.
2. Select the Privacy & Security panel.
3. Under Enhanced Tracking Protection, select the Custom radio button.
4. Check Cookies and use the drop-down menu to select the types of cookies you wish to block.

   

   To block all third-party cookies, select All cross-site cookies (may cause websites to break) from the drop-down.

   Note: Firefox also blocks third-party cookies in ETP Strict mode. This differs from blocking all third-party cookies through the custom cookie blocking settings in technical details. For more information, see Storage AccessAPI on MDN Web Docs.

5. Select the button (shown when multiple tabs are open) to apply your new setting.

   Note: Firefox also includes Total Cookie Protection, which creates a “cookie jar” for every website. This feature keeps cookies in the site where they were created so that they can't track you across websites. Total Cookie protection is enabled when the Cross-site tracking cookies, and isolate other cross-site cookies setting is selected.

Enable third-party cookies for specific sites

Some websites may not work properly when third-party (cross-site) cookies are blocked. To turn off Enhanced Tracking Protection for a specific website:

1. Visit the website.
2. At the left of the address bar, click the shield icon .
3. At the top of the panel, toggle off the Enhanced Tracking Protection switch . This will disable Enhanced Tracking Protection for the site, causing the page to automatically reload and enable trackers.

   

Follow the same process to turn Enhanced Tracking Protection back on.

If the issue persists, consider reporting it by submitting a Broken Site Report. This allows the Webcompat team to examine the problem. For more information, see How do I report a broken site in Firefox desktop?