Portable Document Format File (.pdf) is a type of document created by Adobe back in 1990s. The purpose of this file format was to introduce a standard for representation of documents and other reference material in a format that is independent of application software, hardware as well as Operating System.
Learn more about this file format here
GroupDocs.Viewer (in GroupDocs.Viewer.dll) Version: 20.9
public static readonly FileType PDF
Public Shared ReadOnly PDF As FileType
static initonly FileType^ PDF