Attribution

Attribution is the practice of assigning credit for a conversion across the marketing touchpoints that preceded it.

You rarely get a conversion from a single click. Someone sees a paid social ad, comes back later from an organic search, then converts through an email. Attribution is how you decide which of those touchpoints gets the credit, and how much. In GA4, the model you pick decides how credit gets divided, and that division flows into every report that shows conversions by channel.

Say a purchase follows four touchpoints: Paid Social, Organic Search, Direct, then Email. Under a last-click model, Email takes all the credit. Under data-driven attribution, GA4 splits that single conversion into fractions across all four, so you might see 0.4 credited to Paid Social, 0.3 to Email, and the rest spread over the middle two. Same conversion, very different picture of what worked.

Attribution assigns credit, it does not prove cause. A channel getting credit is not the same as that channel having caused the sale. People conflate the two constantly and then cut a channel that was doing real work upstream. If you want cause, you run a lift test or a geo holdout, not an attribution report.

It is a bookkeeping rule, not a truth machine.