Target Row Refresh (TRR) is a security feature in modern memory chips, especially DRAM, designed to protect against Rowhammer attacks. Rowhammer is a vulnerability where repeatedly accessing (or 'hammering') certain memory rows can cause electrical interference, leading to data corruption in adjacent rows. TRR works by actively monitoring memory access patterns and automatically refreshing nearby rows when it detects frequent access to a specific row. This helps prevent unintended bit flips and enhances the reliability and security of memory systems.