MyDefrag is a disk defragmenter and optimizer (a maintenance utility to make your harddisk faster) for Windows 2000, 2003, XP, Vista, 2008, Win7, and for X64. It is freeware, no time limit, fully functional, no advertisements. Fast, low overhead, with many optimization strategies, can handle floppies, USB disks, memory sticks, and anything else that looks like a disk to Windows. Included are a set of easy to use scripts for endusers, a scripting engine for demanding users, a screensaver, and a combined Windows plus commandline version that can be scheduled by the Windows task scheduler or for use from administrator scripts.

MyDefrag is extremely solid because it is based on the standard defragmentation API by Microsoft, a system library that is included in Windows 2000, 2003, XP, Vista, 2008, and Win7. Most defragmenters are based on this API, including the free defragmenter that comes with Windows and many commercial defragmenters. Basically all MyDefrag does is send "move this file to that location" commands to the API. The API is part of the operating system and can safely move almost any file on the disk, without risk and while the computer is in full use.

Defragmention
Imagine a book split into several parts, some pages are over here, other pages in another room on another floor altogether. You will have to walk a lot when you need to read the book. It may sound silly, but this is exactly what happens to files on your harddisk. Defragmentation will put all the parts (fragments) back together, making your computer a lot faster.
Optimization
Imagine a big library with lots of books, spread out all over the building and not sorted whatsoever. There is an index telling you exactly where every book is, but you will have to walk a lot when you need several books. This is exactly what happens on your harddisk, the files that belong to an application can be all over the place, anywhere on the harddisk. Optimization will bring all the files together in one place, leaving the rest of the harddisk empty, and will sort the files, for example alphabetically.

Defragmentation and optimization will not only make a harddisk faster, but also lengthen it's life span, because the disk will have less work to do and therefore have less wear and tear. Also, it will refresh and strengthen the magnetic data on the harddisk by simply reading the (weakened) data and writing it afresh. However, defragmenting and optimizing is work, so excessive defragmenting and optimizing can actually cause more wear and tear than it prevents.

* On most harddisks the beginning of the harddisk is considerably faster than the end, sometimes by as much as 200 percent! You can measure this yourself with utilities such as * HD Tune. MyDefrag is therefore geared towards moving all files to the beginning of the disk.
* MyDefrag organizes files into zones, such as directories, Windows files, files used while booting, regular files, and rarely used files. The most accessed files are placed at the beginning of the harddisk, and files that are commonly used together are placed in close proximity to each other. This results in a dramatic speed increase, and is in fact more important than defragmentation. The program comes with scripts with a zone organization suitable for most users, power users can customize the zones through scripts.
* Sorting the files on your disk can give you even more speed. There are several sorting strategies to choose from. Most of them will take a lot of data shuffling, taking a lot of time for MyDefrag to complete, and therefore should only be used occasionally.
* A running computer will create and delete temporary files like there is no tomorrow. If the harddisk were completely optimized then the only place for new temporary files would be behind all the other data. Which is rather slow. MyDefrag can maintain free spaces at various locations on the disk to make temporary files faster.
* Windows reserves a percentage on NTFS disks for the MFT (Master File Table), but can place normal files there if the rest of the disk is full. The files will remain there, even when there is enough space again. MyDefrag can look for files in the NTFS reserved areas and move them to normal diskspace, making the reserved areas available again for the MFT.