Your computer performs a lot of tasks by itself, usually at night. It may use Windows Update to see if there's any new files Windows needs. It may download the latest antivirus software definitions, or it may even restart itself.
Defraggler lets you schedule its operation so that you can run it while you're not at your PC - whether it's late at night, early in the morning, or any time of day.
As with other Windows programs, Defraggler uses the Windows Task Scheduler to enable you to set it for future defragging. Simply tell it how often you want it to defrag a drive (once, daily, weekly or monthly). Then it will go ahead on its own, tirelessly defragging your computer whenever you need it to.
If you want more options, Defraggler also lets you defragment multiple drives on the same PC, using different schedules. You can defragment your main C: drive every night, and your external D: hard drive every week. It's up to you.