This is a format for presenting fonts in PDF files that was initially conceived to store symbols in the Japanese and Chinese languages because it had a 16-bit structure and allowed for more precise adjustment. CID expands the the potential for PostScript by supporting languages that do not have a left-to-right orientation, and by supporting even a vertical mode of orientation.
This is a standard TrueType font format developed by Apple Computer in 1989. The advantage of TTF till now has been its high level of font display control right up to the pixel. It has a vector format so it’s easy to scale. Today TrueType is used in operating systems from Apple to Microsoft.