What Is a .PDF File?

by Justin H. Pot

If you find a .PDF file, that document is as close to a paper document as you can find on the web. The PDF standard was invented by Adobe, and evolved into the thriving open standard it is today. A PDF, or, as it's known in long form, Portable Document Format, looks the same on every operating system and in a variety of readers. This is accomplished by embedding everything into the file: the fonts, the graphics and layout instructions.


The PDF's beginnings were very humble. Adobe programmers developed the format internally so they could have a way to distribute documents amongst Adobe staff members, on any computer running any operating system. This became the PDF, and the Acrobat software suite was released to create these files in 1991. The technology was pricey: $695 for the person version and $2,495 for the professional version. Even the reader alone cost $50 (today the reader is free.) Through the years Adobe refined the product, which gained a huge following in the publishing industry.


The advent of the Internet really caused the PDF format to take off. Unlike standard HTML documents, PDF documents looked the same on every computer. This, combined with a free plug-in Adobe created for Netscape, made PDFs a standard part of the web experience. Adobe developed the format to work better on the web, allowing PDFs to include links to HTML files and HTML files to include links to PDFs. This cemented the format as a web staple.

Current adaptation

PDF usage online continues today. Adobe claims there are 200 million PDF documents on the web. The format is also widely used in the publishing industry as a way to transport documents ready to be printed. It can safely be called a de-facto standard for that purpose.


The PDF became the ISO-32000 standard in January of 2007. This meant the format was recognized as an open standard usable across the planet, and that those working with PDFs have to follow the ISO specifications as to how the files should be formatted. It also serves as a guarantee that PDF files created today will be readable for years to come.


If you need to open a PDF file, the best tool may be Adobe's free Reader software. If that doesn't suite your preference, some good alternatives include Foxit Reader or Sumata. Check out the resources section of this article for a complete rundown of alternative Windows PDF readers. Mac and Linux-based systems come with the ability to read PDFs by default; so, if you're in one of those camps, just double-click the file.

About the Author

Justin H. Pot is a freelance journalist, writer and blogger based in Boulder, Colo. He's written for local newspapers in the United States and his native Canada, and also blogs for the environmental website Ecohearth.com.