New article by RMS, "When free software depends on non-free"
Richard Stallman's latest article, When Free Software Depends On Non-Free discusses different kinds of free software "traps" — when a free program's use depends unavoidably on a nonfree program — including the subtle but nefarious problem in which upgrading a free program requires using a nonfree programs. Stallman's various examples of different kinds of traps will help you be able to recognize them, and as he concludes in the article, "all it takes to avoid the trap is to recognize it."