Wear Leveling
An SSD-controller technique that spreads program/erase cycles across physical flash blocks to reduce premature wear of heavily used cells.
Flash cells have a finite program/erase endurance. When the same logical region changes repeatedly, the controller can move data so that one physical block does not absorb all of that wear.
Dynamic wear leveling redistributes actively changing data; static schemes can also move long-lived data when needed to balance erase counts. The practical result is that a host logical address does not have one permanent physical location.
The mechanism belongs with the Flash Translation Layer, and its sanitization implications are discussed in SSD and NVMe Media Sanitization and Cryptographic Erase.