When you defragment a partition in Windows 10, the files stored on it are rearranged to occupy continuous storage locations. This process minimizes the time it takes the hard drive to find all the fragments of your files, thereby decreasing the time it takes you to access them. The startup time for Windows is also improved.
USB drives and SSDs have a limited number of read/write cycles, so don’t use up your cycles by defragmenting. Doing so isn’t necessary, which is why the Optimize Desktop app doesn’t show you those types of drives. You can use the Optimize Drives tool only to optimize partitions on classic hard disks.
Although Windows automatically defragments your drives in the background once a week, you can also choose to defragment manually. Here’s how:
In the search bar on the taskbar, type defragment.
A list with search results appears.
Click the Defragment and Optimize Your Drives search result.
The Optimize Drives window appears.
Defragmenting a partition.Select the partition that you want to defragment.
Click Optimize.
The process may take a couple of minutes to finish because it includes several optimization passes.
When the process finishes, click Close.