Everybody needs diagrams. Most users need to create one more
often than they think: that flowchart for a presentation, that
sketch of the bird feeder to build this weekend, or a time line.
Getting more technical, there are always circuits and blueprints
and the like. Stop wasting time with an office app, the GIMP, or
a paint program: use Dia, an easy yet powerful made-for-diagrams
editor. If you're running GNU/Linux, then just snag Dia from
your distribution's repositories. If you're using Windows, then
it's more complicated: your best bet is following these
instructions to install Dia on Windows. Open Dia up, and--well,
nothing fantastic happens. Just like most programs, you'll see a
canvas, a toolbox, and a toolbar to open, save, copy, get help,
etc. The canvas has pretty little squares, to check the scale
and orientation of things you draw. The toolbox might seem a bit
different. Even still, it really doesn't seem to be quite
enough. Let's explore what you can do with it. I already
mentioned the canvas. If