What is fonts "embedding" PDF documents often contains text written with various fonts. In order Acrobat Reader or another pdf viewer can display this text, it must have access to font files used in the document. If the OS where you open the document doesn't have needed fonts, the document may become unreadable. For the sake of resolving this issue, the PDF standard allows to copy font files into a pdf document, thus providing the guarantee, that wherever you open this document, fonts will be available and the document will be readable. This copying of font files is called "embedding". Of course, here a problem appears: font files usually occupy much space and a pdf document may be become unacceptable because of big file size. The PDF export in FR4 is capable to embed fonts, but it does that in the simplest way, by just copying all needed font files into a document. Sometimes, this leads to increasing the file ...