What is server-side tracking?
With regular tracking, the visitor's browser sends data to Meta, Google and other tools. With server-side tracking, that goes through your own server. You then decide which data goes where.
Why it matters
Browsers and ad blockers block more and more measurements. As a result, ad platforms know less well which ad led to an order. Measuring through your own server makes the link between ad and order more reliable, provided you respect the visitor's consent.