“Anyone who uses X windows at all needs a window manager
(WM). Not everyone needs the same window manager though – it often
depends how you use X. If you just jump in from time to time
to use a particular GUI tool, then something simple in design with
minimal frills is adequate. If you have a low-spec machine, or you
need to use the resources elsewhere then you need a lightweight WM
with a small memory footprint. Of course, there are always people
who want the flashiest WMs with the most functions and the nicest
graphics, or they may just have processor cycles to burn with their
souped-up machine. These people will be looking for a pretty WM
with little worry about how much of a hog it is!”
“So what sort of range of WMs are there out there. The simple
answer is lots. A quick look on freshmeat.net reveals that in their
Window Managers category there are 28 entries – some of these are
variations on other WMs, but this is still quite a lot….”