What is a PDF?
A PDF file is a file that typically exists in a format that cannot be changed and yet is readable by most people.
PDF stands for Portable Document Format and the format was created by Adobe Systems in around 1993. The aim was to make it possible for people to create documents complete with formatting and then deliver them to other people in a way that would preserve the original format no matter what device the document was printed out on.
The advantage of PDFs is that you can be sure that if you send someone a PDF they will view it as you intend: the fonts will be what you specify, the font sizes will be as specified. Any images will appear in the right place and so on, yet the reader will not readily be able to edit the document. In fact you can put password controls onto PDF documents too to stop unauthorised people reading them.
Internet Marketers like using PDFs as free reports because they have a higher perceived value than a web page yet they can include links to websites in the text. This means that a marketer can create a free report about something and in that report refer to a product that he is an affiliate of. He can do this in such a way that when the reader clicks on the link in the report to find out more about the product, they go via the report creators affiliate link. Any subsequent sale that arises generates a commission for the writer.
One standard internet marketing technique is to allow affiliates to brand or rebrand links in PDF files so that they become affiliate links. For example, the author of an ebook may place links to his website in the book and use rebranding tools to allow affiliates to turn all these links into affiliate links. Anyone reading the ebook online who clicks a link and buys something from the author will then generate a commission for the affiliate who distributed the ebook.