Advanced Persistent Threat

An advanced persistent threat (APT) is a skilled attacker who breaks into a network quietly and then stays hidden for a long time, often months, to steal information or watch what an organisation does. The name says what makes it different: the intruder is advanced, they persist rather than grab and go and they are a real threat with proper backing, usually a foreign government or organised crime.

Think of a burglar who does not smash and run but quietly copies your keys, moves in and lives in the spare room for months, taking what they want a little at a time. Because the aim is long-term access, this kind of attack is judged by how well it hides and how long it lasts, not by any one clever trick. If you hold data worth spying on, the danger is not just a quick break-in but someone settling in unnoticed.