A quote from Steve Jobs biography.
Because he [Jobs] believed that Apple’s great advantage was its integration of the whole widget—from design to hardware to software to content—he wanted all departments at the company to work together in parallel. The phrases he used were “deep collaboration” and “concurrent engineering.”
Instead of a development process in which a product would be passed sequentially from… design to manufacturing to marketing and distribution, these various departments collaborated simultaneously. “Our method was to develop integrated products, and that meant our process had to be integrated and collaborative,” Jobs said.