Automobile technicians are in demand to repair the software that now powers our cars; manufacturing technicians, to upgrade the numerically controlled machines and 3-D printers that have replaced assembly lines; laboratory technicians, to install and test complex equipment for measuring results; telecommunications technicians, to install, upgrade, and repair the digital systems linking us to one another. Technology is changing so fast that knowledge about specifics can quickly become obsolete. That’s why so much of what technicians learn is on the job.