Many of you have downloaded and used the free Adobe Acrobat Reader. The IRS uses the pdf format to post all of its tax forms on the Internet.
Portable documents are just what they sound like portable.
Let's say that I create a document in Microsoft Word 97. It has tables, graphics, a few fancy fonts and really, really complex formatting. I hand this masterpiece.doc to you on a disk, or send it to you as an e-mail attachment. The trouble starts. You don't have Word97.