Portable Document Format files, a file format that preserves document formatting across different devices and operating systems.
Acronym created by Adobe Systems in 1991, combining 'portable' (easily carried/transferred), 'document' (written record), and 'format' (structure/arrangement). Designed to solve the problem of documents looking different on different computers.
PDFs were revolutionary because they solved the 'what you see is what you get' problem that plagued early computing. The format is so successful that it's become a verb - people routinely say they'll 'PDF' a document, turning a corporate acronym into common language.
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