“Early Binding” workflow means that RGB image data are converted into the planned CMYK print colour space as early as possible during separation. Usually this is done in Photoshop, and the already separated image data is then placed in InDesign.
In the best case, this results in a layout document completely built up in the CMYK output colour space, which can be exported directly into a PDF file in the output colour space without colour space conversion.
If, however, the output colour space is changed at a later point in time, for example because printing is to be done on uncoated paper instead of image printing, all images must be completely rebuilt and imported or embedded. Therefore the “Early Binding” workflow is considered inflexible and not media-neutral.