Fragmentation lowers your performance as the system needs to time to search through all the scattered files. Fortunately Windows has a defragmentation software inbuilt. You can access this by going to Start Menu --> Programs --> Accessories --> System Tools and then selecting Disk Defragmenter.
Another way is to right click on the drive you want to defragment and then select properties and select the tools tab. There you will find the option to defragment the drive.
Here I am going to show you how to add the degragment option to the right click menu or the context menu when you right click on any drive. You have to edit the registry to get this option, so be careful.
Now to do this
--- Go to registry editor by typing regedit in start menu --> run and hit enter.
--- Then in the left pane find this key HKEY_CLASSES_ROOT\Drive\shell
--- Now right click on the key Shell and create a new key and name it Defrag.
--- Now create a sub-key under defrag by right clicking on it ans selecting new key and name it Command.
--- Now select command and in the right pane double click on the default valued entry.
---Enter defrag.exe %1 in the value data field for Windows XP and enter dfrgui.exe %1 for Windows Vista.
--- Click OK and close the registry editor.
You can check by right clicking on any of your hard disk drives. You will see this option.
Now you can easily defragment your drives by just right clicking on them.