The process of identifying which events (e.g., impressions and/or clicks) should be associated with influencing a subsequent conversion. Several different attribution models exist that can determine how much credit will be given to previous events. Last click/view attribution models (also known as last seen) give all of the credit to the most recent event prior to the conversion. First click/view attribution gives all of the credit to the first impression delivered to the user. Fractional Attribution gives some amount of credit to each of the prior events associated that a user's subsequent conversion.