the.com/free software
free as in speech, not free as in beer — though it's often both.
means software licensed so anyone can run, study, modify, and share it, source code included, no permission needed.
from coined by richard stallman in 1983 when a printer driver he couldn't fix without source code drove him to launch the gnu project and, later, the free software foundation.
the four freedomsrun, study, modify, redistribute — numbered zero to three
copyleft trickgpl license forces derivatives to stay free too
linux backboneruns most servers, all android phones, the internet
not same asopen source cares about code, not ethics