What’s the most important component of your computer? RAM? Processor? Monitor? How about your hard drive? As well as being home to Windows itself, your hard drive is where you store all of your documents and it is a piece of hardware that it in constant use whenever your computer is switched on.
The problem with any hard drive is that files become fragmented – they are broken up into a series of small chunks which have to be pieced together whenever they are accessed. This is a serious bottleneck to performance and it is not a problem that can be tackled without the right tool.