What is third-party cookie?
Have you ever wondered why websites suddenly start serving you ads for specific products everywhere you browse? For example, after you visit an eyewear website or search for glasses on Amazon, you'll notice you get a lot of ads related to eyeglasses or sunglasses. This is done using third-party cookies stored on your device which are primarily used for targeted advertising.
Why do you need to disable third-party cookie?
They track your browsing activity across different websites, building a profile of your interests to be used by advertisers to serve you ads that are more likely to be relevant to you. As such, they raise significant privacy concerns because they allow companies to track your online movements across multiple websites, building a detailed profile without your full awareness.
How to disable third-party cookie?
While Firefox and Safari browsers have blocked third-party cookies by default for quite some time, Google Chrome, on the other hand, had a deadline to phase out third-party cookies by the end of 2024. However, Google recently announced that it is delaying the phase-out of third-party cookies beyond 2024 (https://searchengineland.com/google-third-party-cookie-phase-out-third-delay-439864)
If you are a Chrome browser user like me, you don’t need to wait for google to phase-out third-party cookie. You can actually disable it in Chrome browser by typing "chrome://settings/cookies" on the address bar and selecting "Block third-party cookies." I've had this setting enabled since its introduction and haven't encountered any significant website functionality issues. Once you do that, your browser address bar will show a blocked icon for every site you visit that uses third-party cookie as shown below …
More interestingly, the following is a screenshot of my login session with my bank (a major US bank) website. As you can see the bank’s webpage code indeed has embedded content from facebook.com. However, since the third-party cookies are blocked, it will not be able to read which is what I want. As a matter of fact, this is indeed how Facebook learned about my banking activity which I have documented in detail in a blog post last year. You can read it at https://blog.selvansoft.com/2023/06/facebook-knows-you-way-more-than-you.html to learn how the information was gathered.
Ideally, I’d like to block facebook.com here all together (i.e. disable it like I did with public.cobrowse.oraclecloud.com). However, it is not very practical because if I do that, I need login & authenticate to facebook.com every single time which is painful, so I let it be there at least I know they are not going to learn my banking activity for sure which is good enough.
Finally on a related cookie topic, I learned an interesting fact from a tech podcast with Steve Gibson (grc.com) on the annoying cookie permission pop-ups (GDPR compliance) we see on every website these days. It turns out that about 65% of the websites ignore what you choose and place tracking cookies anyway. You can view/hear the relevant section of the podcast here and here.
