Advanced Persistent Threats (APTs) are targeted, stealthy cyberattacks designed to infiltrate and extract sensitive data from organizations, particularly those dealing with valuable information. They follow a systematic lifecycle involving reconnaissance, initial access, establishing footholds, lateral movement, data exfiltration, and persistence, making them a significant cybersecurity challenge. To defend against APTs, organizations should focus on proactive vulnerability management, advanced threat detection tools, employee training, network segmentation, and continuous monitoring.