Many years ago I noticed a work colleague was doing something on his PC that entailed lots of coloured rectangles on his screen. I asked him what it was and he told me it was a tool to view disk usage. It looked really useful so I asked him where he got it and all he said was it was a commercial piece of software. I’ve been looking for something like it ever since.

Until recently. I was searching the net for something, I forget what, when I came across a mention of Tree Maps. From here there was a link to SequoiaView. This is a freeware utility that produces a Tree Map of your PC’s hard drive. It’s pretty much what I was looking at all those years ago and it is incredibly useful.

The thing about Tree Maps is that they represent proportion by area, and in a nested fashion. This means you can very quickly track down big space users. It’s hard to explain more than that, so just go try it out.