4b0df59f_com___The_Crucial_SSD_glossary__Description
[Title] Wear Leveling [Description] 
Wear Leveling ensures that all NAND cells on a flash-based device are used evenly, which prolongs the life of a memory card, flash drive, or SSD. How wear leveling works is that data is stored in a certain part of each cell and each cell has a limited life. When data is consistently accessed from the same cell (location), it gradually wears the cell out over time. Wear leveling technology allows data to be disperesed more evenly and thus avoid wearing the cells out.
uk.crucial.com - The Crucial SSD glossary
Description