Portable Document Format (PDF) has become a defacto standard for document distribution and archiving. PDF was developed by Adobe Systems. Adobe Systems retained tight control oer PDF until 2008 when it became an ANSI/ISO standard. Since then, dozens of companies have getten in the the PDF game. So far though, none are as good as Adobe at supporting PDFs.
There are at least nine distinctly different file types that all share the monicker (and extension) PDF. Different types of PDF are optimized for different purposes. The most basic is good for archiving. At the top of the PDF world is the XFA PDF, which functions as an application. Only Adobe Systems supports all known PDF flavors.
Most PDF editors only support some PDF types. Only Adobe Acrobat Reader DC and Adobe Acrobat Pro support XFA PDF. This site brings together the best of the World of PDF.