What is defragmentation, you ask.....Defrag (short for defragmentation) is a process that reduces the fragmentation of your computer. In even more simple terms.....when you're saving files on your computer, and that file doesn't save in one unit, but will save as several units.

Take this picture for example:

The purple bars indicate the file you just saved, and the white bars would indicate the free space you have available.

A file that wasn't fragmented would look like this:

There are progams you can run to help you defrag your computer. One in particular that does the job, and does it much faster than the defrag program Windows provides you with is Auslogics. It's free and provides you with a defrag status, so you can see the progess. It also gives you a visual of how fragmented your computer is and how it will look afterward. I use this program for both my computer at work and at home. Hope this works for you as well.