What is file linking?
When an image is imported into a layout program, Quark for example, the image is considered linked to the document. When the Quark file is opened and sent to an output device, any linked image in the document is referenced by the output device for imaging. If the linked image is not present, the Quark document will not be able to print the file correctly. Linked images must be included when a document is submitted for digital output.