An Advanced Persistent Threat (APT) is a sophisticated and prolonged cyberattack, typically orchestrated by well-resourced groups such as nation-states or organized criminal organizations. These attackers infiltrate networks using advanced techniques, remaining undetected for extended periods to steal sensitive information, spy on activities, or disrupt critical operations. APTs often target governments, corporations, or infrastructure, using custom malware, social engineering, and other methods to achieve their goals. The persistence and skill of APT actors make them particularly dangerous and challenging to defend against.