Who or what is a 'defrag', I hear you say? Defragging or defragmenting your hard drive is a way of speeding up your PC or laptop in Windows - in principle, at least. The idea is that as data is saved and resaved to the spinning disc in your hard drive, small packets of information are deposited in random places all over the platter. This then takes longer to read, when Windows calls upon your hard drive to find out information.
By defragmenting or compacting that data the operating system removes the gaps between packets of data, moving it all closer to the middle of the disc. This in turn makes each access of the hard drive quicker, by a tiny amount. It should improve the speed of your PC or laptop, even if it does so by only an imperceptible amount. And that should help the most when it comes to startup times.
Should I defrag?
If your PC or laptop has an SSD rather than a spinning hard drive, NO YOU SHOULD NOT. It won't help, and it will reduce the life of your SSD.
For those with PCs and laptops that have only spinning hard drives (also known as HDDs), it's worth doing. But don't expect a miracle. I've personally never noticed any difference after a defrag, but it definitely can't hurt your PC's performance. Windows 7 users will notice a bigger difference in terms of startup times, because Windows 8 is built to go to sleep rather than shut down. (And if startup times are a problem you are much better off following the advice in this article: Speed up your PC: stop programs starting up when Windows 8 boots.)
But defragging is probably a good thing, and definitely not a bad thing. Here's how to defrag Windows 7, and how to defrag Windows 8.
How to defrag Windows 7
Click the Start button. Select All Programs, then Accessories. Choose System Tools, and then select Disk Defragmenter.
You'll probably have to put in your administrator password. Then hit Defragment Now.
And that's it. Disk Defragmenter will take a while, possibly even hours, to run through, but you can use your PC throughout the process.
How to defrag Windows 8
If it has a hard drive your Windows 8 PC, laptop or tablet will defrag itself by default every week, thanks to the scheduled task: Optimize Drives. So if you haven't changed any settings, you shouldn't need to defrag. But if you aren't sure and you want to check the status of- or manually defrag your drive open Search (Windows+Q or swipe in from the right and open the Search Charm). Now type in 'Defragment'. One of the results will be 'Defragment and optimize your drives'. Select this.
You'll see a dialog featuring a list of the hard drives in your PC or laptop, their media type, when they were last defragged, and how fragmented they are. You really need to defrag only if the drive is more than 10 percent fragmented. (On my severa-years-old work desktop, the two drives were both at 0 percent due to the regular background defragging.)
If you can't see a figure in Current status, to find out if a particular drive needs to be optimized highlight it and hit Analyze. Then confirm your choice. This will update the Current status column.
If any of your drives is fragmented by 10 percent or more, highlight it and hit Optimize. Confirm your choice. Again this could take minutes or hours, and you can continue to use your PC throughout.