A rule or set of rules according to which credit for sales and conversions are assigned to specific touchpoints in the conversion funnel. An attribution model could assign 100% credit to the last interaction right before the purchase, or the first interaction, or distribute credits across a number of touchpoints.
For Amazon sites, Similarweb knows exactly what products were purchased on each visit. For any other site, Similarweb has an attribution model that estimates, on converted visits, the probability that the viewed product was purchased on the same visit. For example, if a converted visit contains two product views, we will count a partial purchase for each category - X% of a single purchase for the 1st product, and Y% for the 2nd product. Since we can purchase more than one product on a single visit, then X%+Y% can exceed 100%.