What font is used in pdf documents?

There is not one particular font used in pdf documents. The PDF's font is whichever font the designer/creator of the original file used. PDF (portable document format) was created to give you a format for exchanging documents regardless of software, hardware, and operating system. It does this by embedding images, fonts, line art, etc in the PDF, so the font you see when you open a PDF is the one that was used to create it and then embedded when it was turned into a PDF. To check what font is used go to file, properties, and fonts. This reads the original embedded font and will tell you all the fonts used in the PDF, their foundry, and type.