What is a .pdf file?

This extension has been used by more than one format

44 different formats have claimed .pdf over the years, so two files with the same extension aren't necessarily the same kind of thing.

• Acrobat PDF 1.0 - Portable Document FormatVersion 1.0 · fmt/14
• Acrobat PDF 1.1 - Portable Document FormatVersion 1.1 · fmt/15
• Acrobat PDF 1.2 - Portable Document FormatVersion 1.2 · fmt/16
• Acrobat PDF 1.3 - Portable Document FormatVersion 1.3 · fmt/17
• Acrobat PDF 1.4 - Portable Document FormatVersion 1.4 · fmt/18
• Acrobat PDF 1.5 - Portable Document FormatVersion 1.5 · fmt/19
• Acrobat PDF 1.6 - Portable Document FormatVersion 1.6 · fmt/20
• Acrobat PDF/A - Portable Document FormatVersion 1a · fmt/95
• Acrobat PDF/X - Portable Document Format - Exchange 1:1999No version recorded · fmt/144
• Acrobat PDF/X - Portable Document Format - Exchange 1:2001No version recorded · fmt/145
• Acrobat PDF/X - Portable Document Format - Exchange 1a:2003No version recorded · fmt/146
• Acrobat PDF/X - Portable Document Format - Exchange 2:2003No version recorded · fmt/147
• Acrobat PDF/X - Portable Document Format - Exchange 3:2003No version recorded · fmt/148
• Acrobat PDF/X - Portable Document Format - Exchange 1a:2001No version recorded · fmt/157
• Acrobat PDF/X - Portable Document Format - Exchange 3:2002No version recorded · fmt/158
• Acrobat PDF 1.7 - Portable Document FormatVersion 1.7 · fmt/276
• Acrobat PDF/A - Portable Document FormatVersion 1b · fmt/354
• Acrobat PDF/A - Portable Document FormatVersion 2a · fmt/476
• Acrobat PDF/A - Portable Document FormatVersion 2b · fmt/477
• Acrobat PDF/A - Portable Document FormatVersion 2u · fmt/478
• Acrobat PDF/A - Portable Document FormatVersion 3a · fmt/479
• Acrobat PDF/A - Portable Document FormatVersion 3b · fmt/480
• Acrobat PDF/A - Portable Document FormatVersion 3u · fmt/481
• Acrobat PDF/X - Portable Document Format - Exchange PDF/X-4No version recorded · fmt/488
• Acrobat PDF/X - Portable Document Format - Exchange PDF/X-4pNo version recorded · fmt/489
• Acrobat PDF/X - Portable Document Format - Exchange PDF/X-5gNo version recorded · fmt/490
• Acrobat PDF/X - Portable Document Format - Exchange PDF/X-5pgNo version recorded · fmt/491
• Acrobat PDF/X - Portable Document Format - Exchange PDF/X-5nNo version recorded · fmt/492
• Acrobat PDF/E - Portable Document Format for Engineering PDF/E-1No version recorded · fmt/493
• Adobe IllustratorVersion 9.0 · fmt/558
• Adobe IllustratorVersion 10.0 · fmt/559
• Adobe IllustratorVersion 11.0 · fmt/560
• Adobe IllustratorVersion 12.0 · fmt/561
• Adobe IllustratorVersion 13.0 · fmt/562
• Adobe IllustratorVersion 14.0 · fmt/563
• Adobe IllustratorVersion 15.0 · fmt/564
• Adobe IllustratorVersion 16.0 · fmt/565
• PDF 2.0 - Portable Document FormatVersion 2.0 · fmt/1129
• PDF PortfolioVersion 1.7 · fmt/1451
• Acrobat PDF/A - Portable Document FormatVersion 4 · fmt/1910
• Acrobat PDF/A - Portable Document FormatVersion 4e · fmt/1911
• Acrobat PDF/A - Portable Document FormatVersion 4f · fmt/1912
• PDF/UA Portable Document FormatVersion 1 · fmt/2050
• PDF/UA Portable Document FormatVersion 2 · fmt/2052

How to open a .pdf file

• WindowsMicrosoft Edge or any browser
• WindowsAdobe Acrobat Reader
• MacPreview
• MacAny browser
• LinuxEvince, Okular, Firefox

How to convert a .pdf file

• Word can open a PDF and convert it to an editable document (formatting may shift).
• Print → Save as PDF turns almost anything into a PDF.

MIME type

When a .pdf file travels over the web, servers label it with one of these MIME types:

What's a MIME type?

The technical record

For archivists, developers and the merely curious: these are the PRONOM registry entries for .pdf.

Got another one?