Richard Stallman, who published his manifesto in March of 1985, has been known to say that, “with software, either the users control the program, or the program controls the users.” Photograph by Denis Allard / REA / Redux

Unix, one of the earliest computer-operating systems, was developed between the late nineteen-sixties and the early nineteen-eighties, by A.T. & T. Bell Laboratories and various universities around the world, notably the University of California, Berkeley. It was the product of a highly collaborative process, in which researchers and students built and shared their code in an atmosphere of excitement and discovery that was fostered, in part, by an agreement that A.T. & T. representatives had signed, in 1956, with the Department of Justice, circumscribing the company’s commercial activities in exchange for an end to antitrust proceedings. But in 1982, A.T. & T. was broken up and its agreement with the department ended; before long, the company was selling copies of Unix without including the source code from which it was derived, effectively commercializing the operating system and hiding its building blocks within a proprietary program. The move greatly upset many in the programming community, including Richard Stallman, a software developer in his late twenties who was then working at M.I.T.’s Artificial Intelligence Laboratory.

Stallman was uneasy over the increasing encroachment of proprietary software. He’d seen evidence of it in his own lab, when he found himself unable to adapt a new Xerox printer with a program he’d created to alert users to paper jams, and he believed that he had an obligation to protect and nurture the hacker ethos he’d experienced at M.I.T., which valued intellectual curiosity, esprit de corps, and fun over profit. In late 1983, he posted to two newsgroup discussion forums an idea to create an alternative to Unix. “If I get donations of money, I may be able to hire a few people full or part time,” he wrote. “The salary won’t be high, but I’m looking for people for whom knowing they are helping humanity is as important as money.”

Stallman expanded and formalized his ideas in the GNU Manifesto, which he published in the March, 1985, issue of Dr. Dobb’s Journal of Software Tools, thirty years ago this month. “So that I can continue to use computers without dishonor,” he wrote, “I have decided to put together a sufficient body of free software so that I will be able to get along without any software that is not free. I have resigned from the AI Lab to deny MIT any legal excuse to prevent me from giving GNU away.” The nearly forty-five-hundred-word text called for collaborators to help build a freely shareable Unix-like operating system, and set forth an innovative method to insure its legal protection.

The GNU Manifesto is characteristic of its author—deceptively simple, lucid, explicitly left-leaning, and entirely uncompromising. He explains the point of the project in short, declarative sentences: “[A] user who needs changes in the system will always be free to make them himself, or hire any available programmer or company to make them for him. Users will no longer be at the mercy of one programmer or company which owns the sources and is in [the] sole position to make changes.” The document is also funny, in keeping with the playful traditions of early hackers. For instance, GNU (pronounced “guh-NOO,” with a hard “g”) is a recursive acronym, spelling out “GNU’s Not Unix.”

Stallman was one of the first to grasp that, if commercial entities were going to own the methods and technologies that controlled computers, then computer users would inevitably become beholden to those entities. This has come to pass, and in spades. Most computer users have become dependent on proprietary code provided by companies like Apple, Facebook, and Google, the use of which comes with conditions we may not condone or even know about, and can’t control; we have forfeited the freedom to adapt such code according to our needs, preferences, and personal ethics. “With software,” Stallman still frequently observes, “either the users control the program, or the program controls the users.”

Thus, the “free” in “free software” refers to freedom, not cost—a distinction that is key to understanding Stallman’s career. A few months after publishing the GNU Manifesto, he founded the Free Software Foundation, of which he is still the president. “Proprietary software was the norm when I started the GNU project in 1983,” he told me by phone. “It was because you could no longer get a computer that you could run with free software.”

Now, as a direct result of his work, you can. A home system running exclusively free software today might include, in addition to a GNU/Linux operating system, LibreOffice instead of Microsoft Office, GIMP rather than Photoshop, and the IceCat browser in place of Chrome or Internet Explorer. There is a free version of nearly every software program in common use; more than eight thousand are currently listed in the Free Software Foundation’s program directory. While few such programs are as popular as their proprietary counterparts, interest in free software has increased alongside rising concerns about privacy, as well as about corporate and governmental control over media, culture, and commerce. (A few weeks ago, the technology writer Dan Gillmor published a widely shared piece on Medium about his own efforts toward adopting such a free system.)

Perhaps the most significant innovation in the GNU Manifesto is a method of rights protection known as “copyleft,” which gave rise to GNU GPL software licenses, the first of which was issued in 1989. Under a GPL license, you are free to use, study, modify, and share a software program according to your own wishes, provided (and this is the important part) that any works you make from it are shared on the same terms; you can’t conceal any of it, as A.T. & T. did with Unix. The idea borrows from existing copyright law, but grants protection to users, rather than authors. Stallman wrote:

GNU is not in the public domain. Everyone will be permitted to modify and redistribute GNU, but no distributor will be allowed to restrict its further redistribution. That is to say, proprietary modifications will not be allowed. I want to make sure that all versions of GNU remain free.

Copyleft licenses differ from other software licenses, such as Berkeley Software Distribution (BSD) ones, which also came into use in the late nineteen-eighties, and which impose no such restrictions on proprietary modifications. Such licenses are commonly known as “permissive”—but this means, in a sense, that they permit the future commercial exploitation of users, whose right to copy and share a software work can be restricted by those who make use of it later. (GPL licenses do allow developers to profit from their work; the publishing platform WordPress, for example, is licensed under GPL, and has a for-profit arm.)