In recent years browsers have made traditional advertising tracking harder and harder, through native blocking and stricter privacy settings. Conversions have not disappeared: part of their visibility to those who manage campaigns has.
What is really changing, and why it matters to you
Third-party cookies are small files that allowed an advertising platform to recognize the same user across different sites. With the growing blocking of these cookies by browsers, and with a growing number of users refusing consent to tracking, a part of real conversions stops being visible to advertising platforms.
The practical result: the conversion numbers you see in Google Ads or Meta Ads may be lower than the real ones, and this leads automatic optimization algorithms to work with less information, with a direct impact on campaign results.
Server-side tracking: what it is, in simple words
Instead of sending conversion data only from the user's browser, where it can be blocked by extensions or privacy settings, server-side tracking sends it from a server under your control directly to the advertising platform. This recovers a significant part of the data that would otherwise be lost, while still respecting the consent choices expressed by the user.
Consent Mode: measuring while respecting user consent
Consent Mode is the Google tool that adapts the behavior of tags based on the consent collected through the cookie banner. When a user denies consent, Google receives no identifiable data, but can still estimate in an aggregated and anonymous way the trend of missing conversions, based on patterns observed on users who did consent. It is not perfect, but it is far better than having no data at all on that slice of traffic.
First-party data as the base for the long term
First-party data is the information you collect directly, with the user's explicit consent: an email address left in a form, a phone number, an account created on your site. Unlike third-party cookies, this data stays yours and is more stable over time, because it does not depend on changing browser policies. Building a solid base of first-party data, with the right consent, is today one of the highest-return activities in the long run.
How to start without overhauling everything at once
You do not need to rebuild the whole tracking setup overnight. The path I usually follow starts with an audit of what is measured today and with what margin of error, then activates Consent Mode if it is not already present, and then evaluates whether the volume of conversions justifies the investment in complete server-side tracking, which makes sense especially above a certain monthly advertising budget threshold.