The NeXT software that Apple acquired with the purchase of Steve’s company provided the engine for all of Apple’s future product development. It became the glue that holds together all the Apple devices as a family—which meets the textbook definition of a product family as a grouping of products whose similarity in resource usage, design, and manufacturing processes facilitates planning on a combined basis.
When Steve left Apple, one of the people he brought along to NeXT was Rich Page, who had been chief designer of the next-generation Macintosh. Rich had been one of the four Apple Fellows, a recognition given to contributors who have played an especially valuable role in developing Apple technology. He was responsible for developing tools, including compilers and hardware, for the first prototyped portable—the color Mac.
His contributions at NeXT included what’s called product line engineering, or domain engineering, which refers to product lines that are based on common software, reworked for each product as needed.