PDF literally means Portable Document Format and was created to allow users to exchange documents in an easy way.
To write your documents with the file extension pdf you just need the right software, that you can easily download from the Internet.
Why using it?
Because it is widespread since 1990 and used almost by everybody.
That means that you are sure your documents will be read by the persons you address them to.
Your files can be read on any operating system (Windows, Apple , Linux), support any link and can also be encrypted, you can password protect them, and you can be sure that your documents are safe.
Also the pdf conversion is very easy.
You can create PDF files from any application that can print.
You can convert word to pdf,and convert pdf to word , just with a few clicks.
Sometimes the secret of doing things well is having the right software.