PDF: Portable Document Format
Portable Document Format, or PDF, is a file format developed by Adobe in 1992 that can display text-formatted documents (including images) independent of application software, hardware, and operating systems.
It was a proprietory format owned by Adobe until 2008, when it was standardised as ISO 32000.
The content of PDF files may vary from flat text and graphics to logical structuring elements, interactive elements such as annotations and form-fields, layers, rich media (including video content), three-dimensional objects using U3D or PRC, and various other data formats. The PDF specification also provides for encryption and digital signatures, file attachments, and metadata to enable workflows requiring these features.