Erast Benson <firstname.lastname@example.org> writes: > Explain please. > > Lets assume you have GPL-ed project dpkg. Any change to foo.c must be > contributed back to the community. No. Any change to foo.c can be kept entirely private if you wish. The GPL only requires that *if* you choose to distribute your modification, you must do so with full source code and under the terms of the GPL itself.