Though you can create PDF files on a Mac, it is not always possible on a PC unless you have dedicated software. This is where online PDF creator sites can be very useful.
They are also useful if you for example have been sent or downloaded a Microsoft Publisher file and you have a Mac, or you don’t have Publisher on your Windows PC. They can take the Publisher .pub file and print it as a PDF.
One such site is PDF Online, which can convert a range of file formats (including Microsoft Publisher and Microsoft Office) into a PDF which is then e-mailed to you.
I would suggest that if you do use such a service that you use a disposable e-mail address, or one that can be deleted later.