First Party vs. Third Party Cookies: What’s the Difference?​

First Party vs. Third Party Cookies

Since Google announced it will be removing the use of third-party cookies from Chrome, the world of marketing measurement has been up in arms.

As marketers, we’ve relied on cookies since the dawn of digital marketing. And while third-party cookies are disappearing, first-party cookies will still be alive and well.

But, what’s the difference between first- and third-party cookies? How are they used in marketing? And what does all of this mean for the cookieless future?

We’ll cover everything you need to know, including:

First-party cookies

What are first-party cookies?

First-party cookies are owned by the publisher or website owner and are directly stored by the website (or domain). 

Where are first-party cookies used?

First-party cookies allow website owners to: 

  • collect analytics data
  • remember language settings
  • and perform other useful functions that provide a good user experience

First-party cookie example

  • Let’s say you visited your favourite clothing website a week ago
  • You logged into your account and added a few items to your basket while browsing the website
  • But then left without completing your purchase
  • A week later, after pay day, you revisit the website
  • You can see that your login details have been saved so you can access your account instantly
  • And even better, the items you had saved previously are still in your basket too
  • So, you can simply click through and complete your purchase

First-party cookies are a great tool for creating the best user experience for your website visitors.

By having them activated on the website, and being allowed by the user, they can store information that make things like checkout experiences smoother.

Third-party cookies

What are third-party cookies?

Unlike first-party cookies, third-party cookies are created by domains that are not the website (or domain) that you are visiting. 

Where are third party cookies used?

Third-party cookies are primarily used for: 

  • personalisation
  • audience targeting
  • measurement
  • attribution

Third-party cookie example

  • You see an advert on TV for a brand you’ve never seen before
  • You decide to check them out so, you visit their website to have a browse
  • After a few minutes, you leave without making a purchase or making an account
  • The next day, as you’re scrolling on Instagram, an ad pops up on your feed for that same brand

Third-party cookies are key for re-targeting website visitors.

They allow you to use information about what they’ve interacted with on your website to deliver personalised ads before they have completed a conversion on your website.

First-party vs. third-party cookies

So, now you have a brief description of both first- and third-party cookies. But what are the differences between the two, and how are they used in marketing?

From a purely technical perspective, first- and third-party cookies are the same kind of file. However, how they are created, used and how browsers interact with them are very different.

We’ve outlined the key differences in the table below:

First-party cookiesThird-party cookies
Who makes them?Cookie is created by the webpage you are visiting.Created by ad servers and other servers loading cookies onto your browser.
Where are they used?First-party cookies only work on the website that made the code.Can be accessed on any website that loads the third-party server’s code.
Who can read them?Only the original website you visited can read them.Anyone with the correct program can read them.
When can they be read?Only when the original user is actively on the original website.Users can read them at any time.

What will happen in the cookieless future?

So, we know that Google’s cookie apocalypse will see the demise of third-party cookies in its Chrome browser. But what doesn’t that actually mean for your marketing?

Third-party cookies are a key part of the marketing ecosystem for many of us, so a few things are going to change when they are removed.

The importance of collecting first-party data will increase as we try to plug the gap left behind. And we may see the the ability to delivered targeted advertising being affected, particularly remarketing, which relies on third-party cookies

As for first-party cookies, they’ll remain unaffected by the change. And as such, are likely to become an even more important part of the marketing ecosystem as they’re heavily relied on to provide actionable behavioural marketing insights.

Google are also introducing their own solutions to the challenges this change will create – but the jury is still out on when they’ll be released and how effective they’ll be as a replacement for third-party cookies.

How to get prepared for the removal of third-party cookies

The first step to preparing for a cookieless future is to understand if you’re using third-party cookies in your marketing efforts at the moment and if so, how and where they are being used.

Once you know that, you can begin to assess your options to ensure your marketing won’t be affected by the change.

If you’re currently using Google Analytics, then your marketing measurement is going to be at risk when the change comes into force. So, starting to look for a replacement now is key to futureproof your marketing.

As a starting point, you can download our eBook ‘Is Cookie-Free Attribution a Myth?’, which covers why AI and Machine Learning are key to achieving success in the cookieless future.

Is Cookie-Free Attribution a Myth?