PDF (Portable Document Format) was developed by software manufacturer Adobe Systems Inc. in the USA, the data format is used for exchanging and processing electronically stored and formatted documents with text and images independent of the hardware and software used. One of its special features is that texts and graphics are stored in vector form, meaning that the resolution of their representation is dependent solely on the output device (monitor, printer). PDF files can generally be recognized by the ".pdf" file name suffix. They can be created using the Adobe Acrobat program. The Acrobat Reader is available free for displaying and printing PDF files.