What is web attribution, and do I need it if I already use GA4?

Web attribution links website visits, sign-ups and purchases back to the campaigns and sources that brought each visitor, using UTMs, ad click IDs and a visitor identity. GA4 already covers a lot of this, and for many sites it is enough. Teams usually add a dedicated tool when they need something GA4 makes awkward: reading first touch and last touch for the same conversion, keeping UTMs through a payment gateway redirect, sending each ad network its own click ID with conversions, or seeing website and app results side by side. Linkrunner's Web SDK (beta) does these and gives AI assistant visits their own traffic class. A fair test is to pick one conversion you already report, run both for a few weeks, and check whether the extra detail changes a budget decision. If it does not, GA4 alone is fine. What Linkrunner's web attribution measures: https://linkrunner.io/blog/linkrunner-now-measures-websites-too