Portable Document Format (PDF) is a widespread file format used for displaying documents created on different platforms or applications.
Advantages of this universal format are:
Software that created the original document does not have to be installed on the computer when opening a PDF. All you need is a PDF Reader.
PDF preserves the original layout of a source document. You can avoid changes during repagination of a document when it is opened on another computer. PDF files display with the same fonts and margin settings as the original.
A PDF file may contain additional information (bookmarks, hyperlinks, comments) to make its contents more accessible.
A Hyperlink is a special area that can be activated by a click. Hyperlinks generally lead to another location either in the same document, or in another document, or they lead to a web address. Hyperlinks can also be used for special functions e.g. submitting a form.
Comments are written explanations or interpretation added to a document. Comments can be distinguished by their authors with different colors.