You may be running non-free programs on your computer every day without realizing it—through your web browser.
In the free software community, the idea that non-free programs mistreat their users is familiar. Some of us refuse entirely to install proprietary software, and many others consider non-freedom a strike against the program. Many users are aware that this issue applies to the plug-ins that browsers offer to install, since they can be free or non-free.
But browsers run other non-free programs which they don't ask you about or even tell you about—programs that web pages contain or link to.