The defragmentation is a process that reduces the amount of file fragmentation. It does this by physically organizing the contents of the mass storage device used to store files into the smallest number of contiguous regions (fragments). It also attempts to create larger regions of free space using compaction to impede the return of fragmentation. Defragmentation is advantageous for the PC performance and the boot speed and relevant to file systems on electromechanical disk drives. A SSD disks has no moving file parts, but it's not bad to defrag the Windows Registry.
How toWarning!
After defragmenting the PC must be restarted! Otherwise, do you lost all settings and changes in the registry after compression.
Upon activation of checkbox "Windows restart after defragmentation" - above the Start button - the reboot occurs automatically.