2. The FSF advocates what it calls free software,
which it defines in terms of freedom to do
things you want to do with the software, not
the price of the software.
3. Freedom to use the software for any purpose
Freedom to examine the source code and
modify it as you see fit
Freedom to redistribute the software
Freedom to redistribute your modified
software
4. Free software, as the FSF defines it, is
different from freeware.This term generally
refers to software that’s free of charge, but
not necessarily free as in speech.
5. The FSF philosophy and the licenses it
inspires are often referred to as copyleft.This
is a play on the word copyright, reflecting the
fact that copyright provisions are used to
ensure freedoms that are, in some respects,
the exact opposite of what copyright was
created to do—that is, to guarantee a
freedom of users to copy software, rather
than to restrict that right.
8. The legal expression of the FSF’s principles
comes in the form of the GPL (sometimes called
the GNU GPL).Two versions of the GPL are
common, version 2 and version 3. (The older
version 1 is seldom used anymore.) Both
versions of the GPL apply the four freedoms of
the FSF philosophy to the licensed software.
They also make explicit an implication of those
four freedoms, by stating that derivative works
must also be released under the GPL.
9. This clause prevents a company from wholly
appropriating an open source program. For
instance, many companies make Linux
distributions, and some use Linux kernels
that incorporate bug-fix “patches.”These
kernels, like the mainstream Linux kernel, are
all available under the GPL. No company
could legally release a distribution based o