Intelligence
What is APT?
Advanced Persistent Threat: shorthand for a well resourced intruder, usually state linked, who stays in an environment rather than smashing and grabbing.
An advanced persistent threat is an intruder with the resources and patience to stay inside a target for months rather than grab what they can and leave. The label usually points to a state-linked group, though some financially motivated crews operate the same way.
What separates an APT from ordinary crime is intent and endurance. The group has a specific collection goal, will rebuild access if it is removed, and adapts its tools when defenders catch on. Vendors track these groups under numbered or named designations, such as APT29 or APT41, so that reports from different teams can be compared.