A closer look at Firefox's Tracking Protection feature
Tracking Protection is a privacy feature of the Firefox web browser designed to block certain unwanted elements on sites visited in the browser.
All Firefox users have options to control Tracking Protection in the web browser; Mozilla announced in June 2019 that Tracking Protection is enabled by default for new Firefox installations, and that it plans to make it the default for existing Firefox installations as well provided that the user has not customized Tracking Protection.
The announcement raised several questions: users wanted to know more about Tracking Protection, whether the system was good enough to make installed extensions superfluous, whether they could uninstall content blockers, and if there was any downside to enabling the feature.
Tracking Protection Basics
Firefox users may customize Tracking Protection functionality in several ways. One of the easier options is to load about:preferences#privacy in the Firefox address bar and check the "content blocking" section on the page that opens.
Tracking Protection offers three presets: standard, strict, and custom.
- Standard (default): blocks known trackers in private windows, third-party tracking cookies in all windows, and cryptominers (as of Firefox 69). As of Firefox 72, fingerprinters as well.
- Strict: blocks the same as the default setting plus Fingerprinters (as of Firefox 69)
- Custom: select what to block:
- Trackers: in all windows, private windows, change blocklist.
- Cookies: third-party trackers, from unvisited websites, all third-party cookies, all cookies.
Firefox displays a Shield icon next to the site address if Tracking Protection is blocking something on the active site. A click on the icon provides an overview of what is being blocked on the page.
The Content Blocking section of the panel that opens provides the following information and controls:
- Tracking Protection status (e.g. custom or standard).
- Whether Trackers, Cookies, Miners, or Fingerprinters are blocked, or partially blocked. Note that Firefox displays only the types that are blocked and not the others.
- Option to look at blocked content.
- Option to turn off Tracking Protection for the site.
A click on a content type that is blocked on the active site displays the list of content that is blocked on it.
Options to interact with the blocked content are not provided but you find a link to the content blocking options in the interface.
Tracking Protection lists and exceptions
Firefox uses lists provided by Disconnect. Level 1 is the default that is used by the browser's Tracking Protection feature.
- Level 1: allows some trackers to avoid site breakage.
- Level 2: blocks all detected trackers. Mozilla notes that this may break "some videos, photo slideshows, and social networking features".
The only option to switch to the level 2 list is to set Tracking Protection to the custom level. Select "change block list" under custom options to do so.
Disconnect maintains a list of trackers that it does not block. If a company runs a tracker on its main site, blocking the tracker would prevent access to the site at all.
You find the current list of unblocked domains here. The list includes sites such as aol.com, gravatar.com, amazon.com, or akamai.com.
There is no option to configure Firefox's Tracking Protection to block these trackers as well. Since you find CDNs on the list as well, blocking them would break sites that rely on these.
Tracking Protection vs. Ad-blocking
Tracking Protection and ad-blocking share some features but are different in others. Mozilla's Tracking Protection approach tries to improve user privacy by blocking certain forms of tracking, namely tracking cookies and a list of known trackers.
Ad-blockers focus on advertisement elements on websites and block these, and by doing so, improve privacy as well as they may block cookies from being set by advertising domains.
Tracking Protection may block some ad elements on websites that you visit but others may still be displayed. A content blocker like uBlock Origin blocks all advertisement on a page by default. Some content blockers, especially Adblock Plus, allow certain ads by default.
Tracking Protection History
- 11.2014 -- Mozilla launches Tracking Protection in desktop Firefox Nightly.
- 12.2014 -- Tracking Protection added to mobile Firefox for Android.
- 03.2015 -- Tracking Protection enabled in private browsing mode.
- 05.2015 -- Study suggests that tracking protection reduces page load time by 44% on average.
- 09.2015 -- Option to select different blocklists added.
- 09.2016 -- Tracking Protection Test Pilot experiment launches.
- 11.2017 -- Tracking Protection launches in Firefox 57 Stable (works in non-private windows)
- 05.2018 -- Optional anti-mining and anti-fingerprinting protections added.
- 06.2018 -- Mozilla plans to push Tracking protection.