First-party data in online advertising: part 1: How they work and why they improve the campaign performance
The cookie apocalypse and the many other attempts at coming up with an original name for the end of third-party cookies in Google Chrome thankfully stopped haunting our LinkedIn feeds sometime in early 2024. What it did do, however, was spark an industry-wide conversation about working with first-party data . That is proving to be a key step toward better measurement and stronger campaign performance today.
The panic around the so-called “dark ages” brought one unexpected benefit: companies started working systematically with their own data and user identification, which opened the door to more accurate and more robust measurement. Paradoxically, we moved away from relying on anonymous or pseudonymous third-party IDs (random strings of characters with no context) and toward a model where we work with real user identifiers instead, such as email addresses or phone numbers (albeit hashed). That makes it possible to match users across devices more effectively, send offline conversions, and measure performance across systems.
| This article is the first part of a five-part series on collecting and using your first-party data in campaigns. In this series, we will cover everything you need to know to make use of them. What first-party data is, how to collect it from your platforms, how to configure its activation in advertising systems, and how to test the whole process. New installments are published continuously on our blog.
Google had actually been warning about dependence on third-party cookies for at least three years. In 2021, it introduced enhanced conversions for the first time in order to improve conversion and user measurement and begin preparing for the planned phase-out (for context: Facebook had already been receiving user data through its pixel back in 2016). That phase-out was eventually postponed, and right now it looks like it may never happen at all. Even so, enhanced conversions still help improve data quality in Google Chrome campaigns and also solve measurement issues in browsers that have been blocking third-party cookies for a long time already.
As a result, virtually every advertising platform that collects data from websites now offers some way of accepting user data to improve measurement quality.
What is first-party data?
In digital marketing, data can be categorized according to who collects it.
First-party data is such that you collect directly yourself — on your website, in your app, or for example in your CRM. A user knowingly provides it to you during registration, purchase, or form submission. Typically, this includes an email address, phone number, full name, or address.
Unlike third-party data, which is collected for example by the operator of an advertising platform, you have full control over first-party data and, when handled properly, the legal basis to use it.
That is exactly the kind of data advertising platforms want today. Each one has simply given it a different name: Google Ads calls it enhanced conversions, Meta uses advanced matching, Bing Ads uses universal event tracking with customer data, while X Ads and Reddit Ads have their own variants usually inspired by Meta.
Behind the different names, though, the principle is always the same. By properly adjusting and extending the measurement script, this data can be passed securely and in a controlled manner into advertising accounts. The platform can then use it either to recover conversions from ads more accurately or to match the user with its own user profile stored in its systems. Naturally, all of this is supposed to happen with respect for user consent. At least that is what they say.
Where do I get it?
User data is created either on the frontend or in a CRM, and media platforms can be “fed” both directly from the website and through CRM imports (already enriched with CRM segmentation for example). For now, let’s focus on data created on the website frontend when a user interacts with the site or app — for example when they fill out a contact form, register, or make a purchase. As the provider of a service or an online store, you need this data to deliver your service to the user. But that does not automatically give you the right to send that email address to a third party — which is exactly what sending enhanced conversions to Google Ads is.
However, if the user gives you consent to pass their personal data to a third party (provided this is stated in your data processing terms and the user agrees to those terms either during the conversion or through interaction with the cookie banner), you may store the identifiers they entered and pass them on. For example to Google Ads.
What is it for and how does it work?
User data allows the platform to assign an event to a specific user.
Without user identifiers, events and their measurement rely on cookies or device IDs, which are becoming less and less reliable. User data provides a more persistent link, especially across devices or browsers.
Source: https://support.google.com/google-ads/answer/12284070#3
Long story short: when you send a purchase event together with an email address, Google assigns it to the correct user already present in its database (for example because that person has a Gmail account). This allows Google to attribute more conversions to a specific ad click, even when the user clicks the ad on their phone and later purchases on desktop, or when measurement happens across multiple domains.
By the way, Google has one more use for user identifiers: Enhanced Conversions for Leads. This is an enriched version of offline import that makes it possible to send conversions to Google Ads even when they happen or are completed off the website.
When should you send it?
User data should primarily be sent with conversion events such as purchases, registrations, or lead form submissions. First, because these are usually the moments when the website operator obtains the user’s personal data. And second, because these are usually the main conversions used to measure business goals. That said, user data can also be sent with every other event, including page_view, as long as it is available.
So it depends on what kinds of data collection opportunities you create on your website. Here are a few tips that actually work in practice:
- Newsletter signup is the most common option. You can place the signup form in the footer, at the end of an article, or as a pop-up.
- Offer an ebook or another valuable lead magnet (guide, template, checklist) in exchange for an email address. This works especially well on educational websites and blogs.
- Community or forum registration brings in data naturally. The user wants access to content or discussion, so the motivation to register is already there.
- A loyalty program or customer account is a typical tool for e-commerce. The user registers to track orders or get discounts.
- A webinar or other online event requires registration, so you collect data even before the actual conversion happens.
- A calculator or another interactive tool where the user enters input data and receives the result by email. This is popular, for example, with mortgage calculators or custom product configuration tools.
The more of these touchpoints you have on your website, the higher the share of visitors you will be able to match, and the more accurate the data you send to advertising platforms will be.
Facebook Pixel prefers sending personal data with every conversion event (including page_view), while Google Ads focuses mainly on primary conversions and does not require an email address for page_view.
Why should I do it, and what do I get out of it?
The most straightforward answer is: you get more conversions in your account. Not because more conversions suddenly happened in the real world, but because the system starts attributing them to your ads correctly. Jaroslav from the previous example bought the book and the ad gets credit for it. Without enhanced conversions, that purchase would simply be missing from the account, and you might throw the campaign away as unprofitable.
That means that platform algorithms are working with more accurate data in practice. Google, Meta, and others optimize campaigns based on conversion signals. The more of them they have, and the more accurate they are, the better they can target, the lower the cost per conversion, and the less money gets wasted. This is not a band-aid for a bad product. It is a simple principle: better input gives better output.
The second benefit is cross-device and cross-browser measurement. If a user clicks an ad on a mobile device but later purchases on desktop via Safari (where third-party cookies do not work), that purchase is effectively invisible to your ad account. With user data, the system can reliably find and match it.
The third benefit is resilience to future measurement changes. Third-party cookies may not disappear from Chrome after all, but Safari has been blocking them for years, Firefox as well, and the share of users on those browsers is far from negligible. And no one knows what is coming a year or two from now. First-party data is under your control, not Google’s or Apple’s.
And then there is one more important benefit: feedback on lead quality. You can send offline conversions to Google Ads as well through Enhanced Conversions for Leads. In other words, the information on whether a lead ultimately turned into a real customer and for how much. The algorithm then stops chasing cheap leads and starts looking for the ones that actually turn into revenue. Which is exactly what you want from campaigns.
A few numbers to close with
The effect of implementing this kind of data transfer into advertising systems cannot be quantified in general terms of course. It will vary from one type of business to another. The technical implementation of consent mode also plays a role - or rather, how high a consent rate you are able to obtain from your customers and visitors. Still, for illustration, here are a few figures from a larger client where enhanced conversions were implemented for Google Ads. Within a single month, the number of recovered conversions increased by roughly 10% in Search campaigns and 15% in YouTube campaigns. At the same time, CPA dropped by around 17% thanks to improved targeting.
If you have a form, registration flow, or e-commerce store on your website, you already have everything you need. You just need to connect it properly - and that is exactly what we will look at in the next articles in this series.
In the next installments, we will cover:
→ Security, hashing, and consent management
→ Correct setup for sending personal data through server-side Google Tag Manager
→ Data upload from CRM (backend)
→ Setup specifics in Google Ads, Meta, Sklik, and other platforms
→ Debugging and how to verify that everything is working as it should
