Advanced persistent threat (APT)

A campaign with a pattern, not a single file. Often patient, often aimed, sometimes state-linked. The persistence is the point.

An APT is a set of malicious activity with shared traits, usually aimed at particular organisations or states over a long period, for money, intel, or politics. Advanced is marketing more often than maths. Persistent is the part that hurts.

You defend it like other intrusion: identity, patching, segmentation, detection that covers dwell time, and IR that can evict without tipping into theatre. Naming a brand does not patch your VPN.