This is a theme that’s been gone over many times, but one more
time shouldn’t hurt: ITWorld’s Joe Barr presents a primer on the
differences between Open Source and Free Software — and more
importantly, why the differences matter. To wit:
If you’re ever confused by, or mixed up the terms,
“open source” and “free sofware,” this is for you. It’s a primer on
the topic of what they are, how they are alike, and how they are
different. So if you’ve heard of the GPL, but are not exactly sure
what it is or what it does, this is for you. Armed with what you
learn here, you will be much less vulnerable to the veritable
barrage of FUD that the Redmondian Empire is hurling at the whole
open source/free software world.