Third-party 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 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.

Note: Cross-site tracking cookies are now disabled by default for all Firefox users. See Enhanced Tracking Protection for more information about how Firefox protects you against 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 How do I turn on the Do Not Track feature?, Enhanced Tracking Protection in Firefox for desktop and Trackers and scripts Firefox blocks in Enhanced Tracking Protection.

Disable third-party cookies

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

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.
Select the Privacy & Security panel.
Under Enhanced Tracking Protection, select the Custom radio button.
Check mark Cookies and use the drop-down menu to select the types of cookies you wish to block.
- Cross-site and social media trackersCross-site tracking cookies — includes social media cookies is the default setting.
- To block all third-party cookies, select All third-party cookies from the drop-down.
Close the Settings page. Any changes you've made will automatically be saved.

Enable third-party cookies for specific sites

Some websites may not work properly when third-party cookies are blocked, even with the default setting Cross-site and social media trackersCross-site tracking cookies — includes social media cookies.

To turn off Enhanced Tracking Protection for a specific website:

Visit the website.
Click on the shield to the left of the address bar.
Toggle the switch at the top of the panel. This will turn off Enhanced Tracking Protection for this site. The page will reload automatically and allow trackers on this site only.