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. That 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. If you are concerned about this, you can disable third-party cookies in Firefox.

Disable third-party cookies

To block third-party trackers or all third-party 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 to choose what to block.
4. Select the Cookies checkbox. Cross-site and social media trackers is the default setting.

   

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

5. 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 Cross-site and social media trackers setting.

To turn off Enhanced Tracking Protection for a specific website:

1. Visit the website.
2. Click on the shield to the left of the address bar.

   

3. 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.

To turn Enhanced Tracking Protection back on, follow the same process.