Third-Party Cookies: A Complete Guide

Third party cookies are cookies that are placed across various websites that are used to track and learn what users are doing online and searching for online. Third party cookies have been around for a long time now and brands have been using them to track website usage and collect user data which not only helps improve the customer experience based on the findings but also helps to improve ad targeting in the process by collecting relevant data about the user including demographics, geographical location, device and browser amongst many others. 

What are Third Party Cookies?

Third Party Cookies are those created by other domains (websites) that are not the current website you are viewing at that particular time. The cookie that is placed on the website you are viewing (by the third party) collects data about the user for the third party website which can be used at a later time. The data collected could be based on user demographics, user browsing history and various other online activities carried out by the user.

Usually used for online advertising purposes, third party cookies are typically placed on a website through some kind of coding script or site tag which embeds the third party cookie onto various other websites in order to collect the data. Cookies and the data they collect are stored on a user’s computer even after they close or log off their browser. Third party cookies allow data to be collected about users beyond that of first party cookies which only track user behaviour when on an owner’s site. 

Here’s a quick example of third party cookies at work.

  1. So a customer goes to and looks at a product page on the site. 
  2. A third party cookie will then track and collect this activity data based on the actions taken by the user. 
  3. The user then leaves the website and visits a completely different website. 
  4. The user will see ads for the same or similar products to which they were looking at on the website. 

This means that the website and the second website the user visits both have a third party cookie embedded on their sites which comes from a third party service (hence being called third party cookies). This third party service could be for example Google Ads who is responsible for creating the cookie and monitoring the site usage.

Third Party Cookies vs First Party Cookies

We’ve covered third party cookies, so let’s take a look at the key differences between first party cookies and third party cookies.  First party cookies are cookies which are implemented and stored by the same website or domain that you are visiting, for example if you visit ‘’ and the first party cookies on the site are owned by them. This allows website owners to collect analytical data such as device usage, language settings, demographic data and many other user behaviour metrics in order to provide a better user experience to its users. 

First party cookies can also be used for other purposes, for example when a user visits an online store and adds an item to their basket, but leaves without checking out a first party cookie can be used by the website owner so that when the user returns to the site again in the future, the item will still be in their basket. 

Third Party Cookies vs First Party Cookies
Third Party Cookies First Party Cookies
Accessibility  Accessible across multiple websites that contain the third-party cookies code. Only accessible when visiting the domain name that created the cookie.
Browser support Supported by most browsers currently, although browsers such as Safari and FireFox now do not support these cookies.  Supported by all browsers. 
Blocking/Deleting Many browsers currently automatically block and delete third-party cookies regularly without the need for the user to carry out these tasks.  Can be blocked/deleted by users but may hinder the experience the user receives. 
Common Uses Advertising, Social Media, Payment Solutions Web analytics, basket/wish lists


How are Third-Party Cookies Created?

So, how are third party cookies actually created if a user is on a different website? In order for a third party cookie to be created on another site, a request is required which needs to be sent between the web page being loaded and the third party server. Depending on the use case, the file which is requested can be in a variety of formats such as an ad (display ad) or even by a tracking pixel (which cannot be seen by the user but acts as a tracking cookie when there is no click event or click redirects are not available) which is usually in the form of a coding script.

Examples of Third-Party Services that Leave Cookies

There are many different third party entities which leave cookies across the web including: 

  • Google Ads Advertising services like Google Ads creates third-party cookies to monitor which websites and content each user is accessing across the internet. These types of cookies are behind the technology which showcases users ads for products and services they have previously searched for.
  • Social MediaA similar approach also works for social media sites where a user can log in to their social media accounts through their device and share content on their social media profiles which then places cookies on that users device. These social media cookies track and collect data about the users behaviours and then uses this to display targeted ads across their social media feeds for the same products and services they were looking for. 

How do Third Party Cookies work?

Third party cookies work by tracking and creating a digital trail of a user’s web history, searches and activity online which can be collected from a single session or across multiple sessions a user completes.  Many browsers automatically allow cookies to track users across the web which offer third party services a means to use this data to send targeted advertisements across various websites and social media platforms. Automatically collecting this data has raised privacy concerns in the past which fall in the remit of GDPR regulations.


How to Clear your Cookies After Each Session

You can however clear your cookies after each session on your browser automatically to remove all of the data and history captured through the use of cookies on various sites you visit. Firstly go to your preferred browser and select the following depending on your chosen option. Not selecting these preferences will mean your browsing history and data associated with your online activity will be preserved and thus continued to be stored and used for third party purposes such as advertising. If you don’t select these settings and preferences across your devices and browsers, each time you visit a website your browser will automatically preserve cookie data from each session. This means you will continue to receive targeted advertisements and other third party services activity. 

Here’s how to change your cookie preferences across browsers; 

  • Chrome – Go into Chrome’s privacy settings and find the ‘keep local data only until you quit your browser’ option to clear your cookies after each session.

  • Firefox – Go into your Firefox browser settings and under the privacy settings select ‘Clear history when Firefox closes’ option to clear your cookies after each session.

  • Internet Explorer – In your Internet Explorer settings, under privacy settings, select the ‘Delete browsing history on exit’ option to delete cookies and browsing data after you close your browser.
  • Safari – Although not automatically you can also clear your browser and cookie data after each session by manually going to settings, to privacy settings and then selecting the ‘Clear cookies’ and ‘Clear cache’ options available.


Why are third party cookies going away?

In a bid to shift away from Third Party Cookies and after growing concerns from consumers surrounding privacy, Google is set to phase out the use of third-party cookies in the Google Chrome browser by early 2024. This deadline has been delayed from previous, after originally being planned for late 2023 which has been down to initial feedback and testing conducted proving that further testing was needed in order to follow through with the original plan. 

It seems as though Google are leading the way to bring an end to third party cookies which could ultimately be replaced eventually with less intrusive solutions which can be used for targeted advertising. Google has introduced plans and is currently building the Privacy Sandbox which aims to be a less intrusive alternative to having third-party cookies. Alongside this, organisations may also need to turn to other alternative services such as Smart Shopping or Performance Max to enhance their advertising effectiveness.

This will then leave a reliance on first-party cookies which heavily favours larger organisations with larger volumes of traffic where they will be able to make better use of first party data due to larger amounts of capital and resources that can be allocated to this area for future development. First party cookies will be the best approach in reacting to the changes from Google.