We all take for granted that everyone knows what a PDF is. But there is a lot more to a PDF than many people realize. PDF stands for “Portable Document Format.” In its most basic form, a PDF is a standardized computer data file format used for exchanging information with others. Because the file format is based on a published standard, it theoretically makes it possible that anyone can open any PDF document as long as the PDF document follows the rules outlined by the standard. The PDF standard is normally referred to as the “PDF specification.” It evolved from a project at Adobe Systems Corporation whose goal was to create a standard format for exchanging documents across diverse computer platforms. Originally, the PDF specification was proprietary to and owned by Adobe, but in later years they released information to the public and relinquished their rights of ownership. Eventually, the International Organization for Standardization (IS0) published a standard for it. The specification has been enhanced over the years to include new features. The first version of the PDF specification was given a 1.0 designation. Subsequent versions of the specification have been developed and named using a version increment of .1 for minor revisions or 1 for major revisions. The current PDF specification version is 1.7. Adobe has complicated the standard by adding its own proprietary extensions with versions numbered using a “Level” numbering scheme. The PDF specifications have been designed so that each version is compatible with all of the previous versions. So PDF documents created using the 1.0 specification can still be displayed by software that implements the 1.7 specification. But the reverse is not true.