Entity resolution is the process of matching records so a system can tell which real-world person, company, device, or account they refer to. It combines identifiers such as names, email addresses, account numbers, addresses, and persistent IDs to decide whether two records are the same entity or different ones.
It matters in cyber security because bad matching can create serious risk: an attacker may exploit duplicate or inconsistent records to hide fraud, bypass controls, or trigger actions against the wrong account. In enterprise systems, weak entity resolution can also cause access-control mistakes, inaccurate risk scoring, and unsafe automation. Defenders use it to link identities across databases, reduce duplicate records, improve fraud detection, and keep AI systems grounded in the correct business context. Strong entity resolution usually depends on clean data, governance rules, and human review for ambiguous matches.