PDF (Portable Document Format, .pdf)
The Portable Document Format (PDF) is the file format created by Adobe Systems in 1993 for document exchange. PDF is fixed-layout document format used for representing two-dimensional documents in a manner independent of the application software, hardware, and operating system. Each PDF file encapsulates a complete description of a 2-D document (and, with Acrobat 3-D, embedded 3-D documents) that includes the text, fonts, images, and 2-D vector graphics that compose the document.
PDF is an open standard, and recently took a major step towards becoming ISO 32000.
When the PDF first came out in the early 1990s, its general adoption was slow. At that time, the PDF-creation tools (Acrobat) and the viewing and printing software had to be bought. Early versions of PDF had no support for external hyperlinks, reducing its usefulness on the World Wide Web; the additional size of the PDF document compared to plain text meant significantly longer download times over the slower modems common at the time, and rendering the files was slow on less powerful machines. Additionally, there were competing formats such as Envoy, Common Ground Digital Paper and even Adobe's own PostScript format (.ps); in those early years, the PDF file was mainly popular in desktop publishing workflow.
Adobe soon started distribution of its Acrobat Reader (now Adobe Reader) program at no cost, and continued supporting the original PDF, which eventually became the de facto standard for printable documents on the web.
The PDF file format has changed several times, as new versions of Adobe Acrobat were released. There have been eight versions of PDF with corresponding Acrobat releases:
- (1993) - PDF 1.0 / Acrobat 1.0
- (1994) - PDF 1.1 / Acrobat 2.0
- (1996) - PDF 1.2 / Acrobat 3.0
- (1999) - PDF 1.3 / Acrobat 4.0
- (2001) - PDF 1.4 / Acrobat 5.0
- (2003) - PDF 1.5 / Acrobat 6.0
- (2005) - PDF 1.6 / Acrobat 7.0
- (2006) - PDF 1.7 / Acrobat 8.0
