'Portable Document Format' was originally created as a way to link all file formats from word proccesors to a variety of image and graphic formats. This was due to the early days of the internet and everyone having different programs and files, so weren't able to open documents that would have been sent to one another.
Today Adobe is more of a tool program to help edit certain images, videos/animations and word based documents and this seems to be the direction in which it's taking with portfolio tools and buisness tools becoming a real proffesional and common program.
