Eric Steven Raymond, widely known by his initials ESR, is an American programmer and writer who became the most prominent public advocate of open source software. On his own home page at catb.org he presents himself as a hacker, open source theorist, and author, and his site serves as the canonical archive of his writings and projects.
His most influential work is the 1997 essay The Cathedral and the Bazaar, first presented at the Linux Kongress in May 1997. The essay’s contrast between centralized “cathedral” development and decentralized “bazaar” development gave the free software world a vocabulary for what it had been doing, and it is widely credited with helping persuade Netscape to release the source code of its browser in 1998.
Raymond was central to the coining and promotion of the term “open source.” By OSI’s own history, he and Bruce Perens jointly founded the Open Source Initiative in late February 1998, with Raymond serving as its first president. The strategy was deliberately pragmatic: to advocate for open development using business-friendly language that set it apart from the more philosophically framed “free software.”
In late 1998 Raymond published the Halloween Documents, a set of leaked internal Microsoft memoranda in which the company analyzed open source and Linux as competitive threats. By annotating and circulating them, Raymond turned an internal corporate assessment into a public argument that open source was being taken seriously even by its largest commercial rivals.
Alongside his advocacy, Raymond is a working programmer; his site documents projects such as the fetchmail mail-retrieval utility, which served as the live experiment behind The Cathedral and the Bazaar. His combined output as essayist, organizer, and coder made him one of the defining figures of the late-1990s open source movement.