Why you need to defrag disk drive?

There are many reasons, why your computer slows down more and more during time.
One of the most important causes is increasing fragmentation of your hard
drives.

Let me introduce What is disk defragmentation,Disk defragmentation describes the process of consolidating fragmented files on your computer's hard disk. Fragmentation happens to a hard disk over time as you save, change, or delete files. The changes that you save to a file are often stored at a location on the hard disk that's different from the original file. Additional changes are saved to even more locations. Over time, both the file and the hard disk itself become fragmented, and your computer slows down as it has to look in many different places to open a file.

There are many tools to defrag drive but in the example here I use the default tools came with windows installation.You can find this tool in System Tools program item on Windows Vista,Disk Defragmenter might take from several minutes to a few hours to finish, depending on the size and degree of fragmentation of your hard disk. You can still use your computer during the defragmentation process.

Conclusion
defragment will increase reading speed,either way to increase system performance.one time in six months may good to run defragment tool.