“Intermediate Binding” workflow means that RGB image data is inserted into the layout during separation, and a colour space separation from RGB into the CMYK output colour space is not performed until PDF export to the print file. Today, intermediate binding is considered a classic workflow for fast, media-neutral layout.
In most cases, RGB layout data is output in PDF/X-3 or PDF/X-1a files.
Alternative workflows are Early Binding and Late Binding.