The PDF story begins with a 1991 internal memo at Adobe Systems in which co-founder John Warnock described a project codenamed Camelot: a format that would let any document be viewed and printed identically on any machine, regardless of the software that created it. The idea drew on Adobe's PostScript imaging model but fixed the output in place, trading programmability for predictability.
PDF 1.0 arrived in 1993 with the first Acrobat release and spread gradually, helped by a free reader and an openly published specification. Governments, courts, and publishers standardized on it through the 1990s and 2000s. In 2008 Adobe handed the format to the International Organization for Standardization as ISO 32000-1, and in 2017 the ISO process produced PDF 2.0 — completing the transition from proprietary product to public infrastructure.