Identity resolution providers use disparate datasets to link information about individuals and households. This is done to target, activate and measure the reach and effectiveness of advertising campaigns. Several different providers perform this function, currently. Yet, the details of it have received little attention. Now, the ARF’s Identity Resolution Working Group, within the Cross-Platform Measurement Council, has issued a report which includes interviews with executives from 20 identity resolution providers. The report sheds light on this crucial part of the advertising ecosystem.