Tesla builds electric cars in giant factories. At its plants, including the battery factory it calls the "Gigafactory," cars and battery packs move down assembly lines where machines and workers add parts in a fixed order. That's mass production: using machinery, assembly lines, and automation to make a large quantity of cars. Mass production is a different choice from an artisan process, where skilled workers build each item mostly by hand, in small numbers, with close attention to detail. A small specialty carmaker, such as Pagani, might hand-build just a few dozen cars a year. Tesla aims to make millions annually. Tesla picked mass production for a reason. To sell electric cars to a wide market at a price many people can afford, the company needs to make a lot of them and keep the cost of each car down.