Press ready PDFs are usually the preferred format for commercial lithographic printers when supplying artwork. Press ready PDFs differ from standard PDFs in that they must meet a certain criteria in order for the file to print without problems. Standard PDFs may include colours that may not print correctly or graphics that are fine to view on screen but will print at a very low quality. Each printer will have their own specifications for supplying artwork. However, it is understood that some rules are standard and all press ready PDFs will need to contain the following: