Rowhammer is a hardware-based cyberattack technique that exploits vulnerabilities in modern computer memory (DRAM). By rapidly and repeatedly accessing, or 'hammering,' specific rows of memory cells, attackers can cause electrical interference that flips bits in adjacent memory rows. This unintended bit flipping can lead to data corruption, privilege escalation, or unauthorized access, even if software defenses are in place. Rowhammer demonstrates that hardware faults can be manipulated for malicious purposes, posing a significant challenge for system security.