If you ship marketing tags from the browser, you have probably watched conversion counts get worse over the last two years. Not because campaigns broke. Because the delivery layer broke. So let me answer the question every PM keeps asking the eng team: what actually is the difference between client-side and server-side tracking, and which one drives business growth? Client-side: events fire from the visitor's browser Vendor scripts load in the page. Cookies are set. Pixels hit each ad platform directly. This model is being eaten by three forces, all confirmed in this Seers AI breakdown — https://seers.ai/blogs/why-businesses-are-switching-from-client-side-to-server-side-tracking/ Browsers block third-party cookies. Tracking pixels lose state. Ad blockers stop tags from firing. The script never loads. Heavy <script> tags slow pages down. That hurts FCP, LCP, INP — and conversion rate with them.…