Introduction

The collection of user data is there to compensate for the loss of data due to the end of third-party cookies. To fully understand the problem, it's important to understand the purpose of third-party cookies.

What are third-party cookies used for?

Third-party cookies enable advertising platforms to create user profiles (interests, consumption habits). These cookies enable Google Ads or Meta to know who is visiting which websites.

In simple terms, third-party cookies link a visitor to a physical person (e.g. Mary) in order to create a user profile based on interests, habits and several other criteria.

The end of third-party cookies

With the end of third-party cookies on Google Chrome (announced for early 2025), the quality of data collected by advertising platforms (Meta Ads, Google Ads, Pinterest Ads, etc.) will decrease.

Indeed, without third-party cookies, a Meta or Google Ads may know that a visitor has bought a product, but won't be able to know that it was Mary (who loves fashion and bicycles) who bought it.

It will therefore be more difficult for advertising platforms to target precise user profiles to offer them relevant advertising (and therefore effective for you as an advertiser).

With these changes, your cost per conversion (CPA) and more generally your customer acquisition cost (CAC) will increase.

The solution: user data sharing

There's a way to tell advertising platforms that it's Mary who has bought, without using third-party cookies. The solution is to send user data.

To compensate for the loss of data due to the end of third-party cookies, you will send your visitors' personal data yourself (this is known as first-party context).

If Mary makes a purchase on your website, you won't just tell the advertising platforms that a visitor has bought a product, but also that it was Mary who made the purchase. For example, by sending Mary's email and phone number.

The more user data you send to advertising platforms, the better conditions you'll be in to seek out performance.

Other examples of user data

Email addresses and phone numbers aren't the only user data you can send.

You can also send :

• first name
• last name
• address
• city
• zip code
• country

Next step

Now that you know what's at stake with user data, let's take a look at how to send it to the server.