Attribution in marketing is the process of assigning credit for a conversion — a sale, a sign-up, a booking — to the marketing touchpoints that contributed to it. The challenge is that most purchases involve more than one touchpoint over days or weeks. A buyer might first find a brand through organic search, return via a retargeted social ad, and finally convert after clicking an email link.
I think of attribution as a budgeting question, not an analytics question. The model you choose decides which channels look profitable and which don't, which decides where next quarter's budget goes. That's why the choice matters more than the dashboard prettiness.
The common models, from blunt to nuanced: last-click attribution gives 100% credit to the final touchpoint and is the default in most analytics tools. First-click gives all credit to the initial discovery channel. Linear attribution splits credit equally across touchpoints. Time-decay weights recent touchpoints more heavily. Position-based (or U-shaped) gives extra weight to the first and last interactions, with the rest spread between. Data-driven attribution — available in GA4 and most enterprise tools — uses machine learning to assign fractional credit based on observed contribution.
The practical risk is that last-click attribution systematically under-credits awareness-stage work (organic content, display, brand video) and over-credits closing channels (branded search, email). If you set budgets on last-click data, you'll keep starving the channels that fed the funnel in the first place. For most service businesses I work with, position-based or data-driven attribution gives a saner picture without requiring a measurement-team rebuild.