Because you don’t want to waste time and bandwidth by accidentally downloading the wrong bit version of your operating system, it is pretty useful to know whether or not your server is currently using a 32 bit or 64 bit version.
To check this via the terminal, run:
uname -m
Its output can be interpreted as follows:
x86_64 = 64 bit
i686 = 32 bit
i386 = 32 bit
Nifty.