Rule or set of rules through which the value that each channel contributes in a conversion or sale is assigned.
There are different attribution models: Last Engagement, Last Indirect Click, Last AdWords Click, First Engagement, Linear, Time Decay, and Based on Position. The most widespread is the last-click attribution model, in which the last click that occurs before conversion is counted .
By detecting the most effective communication and marketing actions, the attribution model allows you to correctly calculate the ROI (return on investment) as well as make a more effective allocation of advertising resources.