When you're trying to clean up your house, it's easy to see right in front of you what needs to be done. If the floor is covered in pet hair, you know it's time to break out the vacuum!
Likewise, if dishes are piled up in your sink, you better get to work on washing them!
Unfortunately, it's a lot harder to see what's making a mess on your hard drive. Bits and bytes can't be visualized so easily as pots and pans.
Windows can show you how many gigabytes you have remaining on your disk, and it even tells you how big any given file is when you hover over it. But you'll need a utility like WinDirStat to show you what it looks like.
WinDirStat scans your whole drive or individual partitions and folders and displays brightly colored squares of various sizes.
The color indicates what kind of file it is and the size indicates how much space it's taking up. This is an easy, straightforward way to visualize exactly what's taking up space on your disk and what's slowing it down.
When you install WinDirStat, it's OK to use the recommended settings unless there's something you know you'd like to change about the setup.
The first time you start it up, it will automatically begin scanning a folder, a partition or an entire drive. You can then view or even delete files from within WinDirStat.