which are then snapped into PC cases rolling down assembly lines. the same parts-power supply units, processors, graphics cards, hard drives, and others can be used to produce various PC models. interfaces are standardized to facilitate production of PCs that are simultaneously differentiated but use standard parts and components, which minimize the cost of manufacturing computers and of designing such as keyboards and of designing new ones. products are standardized worldwide, but elements such as keyboard and software are customized to respond to local language needs.