If you're a programmer and you want to change the software, for yourself or for someone else, you can't.
If you're a business and you want to pay a programmer to make the software suit your needs better, you can't. If you copy it to share with your friend, which is simple good-neighbourliness, they call you a "pirate".
Microsoft would have us believe that helping your neighbour is the moral equivalent of attacking a ship.
The most important thing that Microsoft has done is to promote this unjust social system.
Gates is personally identified with it, due to his infamous open letter which rebuked microcomputer users for sharing copies of his software.
It said, in effect, "If you don't let me keep you divided and helpless, I won't write the software and you won't have any. Surrender to me, or you're lost!"
But Gates didn't invent proprietary software, and thousands of other companies do the same thing. It's wrong, no matter who does it.
Microsoft, Apple, Adobe, and the rest, offer you software that gives them power over you. A change in executives or companies is not important. What we need to change is this system.
That's what the free software movement is all about. "Free" refers to freedom: we write and publish software that users are free to share and modify.
We do this systematically, for freedom's sake; some of us paid, many as volunteers. We already have complete free operating systems, including GNU/Linux.
Our aim is to deliver a complete range of useful free software, so that no computer user will be tempted to cede her freedom to get software.
In 1984, when I started the free software movement, I was hardly aware of Gates' letter. But I'd heard similar demands from others, and I had a response: "If your software would keep us divided and helpless, please don't write it. We are better off without it. We will find other ways to use our computers, and preserve our freedom."
In 1992, when the GNU operating system was completed by the kernel, Linux, you had to be a wizard to run it. Today GNU/Linux is user-friendly: in parts of Spain and India, it's standard in schools. Tens of millions use it, around the world. You can use it too.
Gates may be gone, but the walls and bars of proprietary software he helped create remain, for now.
Dismantling them is up to us.
Richard Stallman is the founder of the Free Software Foundation.