Everything you need to know about commercial print
When PDF started to slowly take over from PostScript, it all started in the commercial print market segment. This is where the roots of the Ghent Workgroup lie – the specifications for the exchange of advertisements and for sheetfed and webfed offset printing where the first specifications developed by the group.
This also means they are quite stable and mature by now. The Ghent Workgroup offers two generations of specifications for commercial print: a more modern one based on the ISO PDF/X-4 standard, and older specifications based on the ISO PDF/X-1a standard.
If you are also doing digital printing, be aware that there are separate specifications for digital print. The requirements and capabilities of digital print workflows are sufficiently different that you are advised to also check out the digital print page.