What is Entity resolution, record linkage?

Record linkage decides which records in two files describe the same entity when no common identifier exists, by comparing their attributes (Fellegi and Sunter, 1969). Entity resolution is the task applied to a dataset’s entity strings (merchants, issuers, apps, vessels) against a reference list, here the security master (Book 7, chapter 4): normalise, compare, and decide to match, to send to review, or to leave unmatched.