About the time of the renneisance, a new way of manufacturing goods had appeared in the world, the Manufactory. Prior to that, it was done by craftsmen in their workshops, where each craftsman worked on one item from start to finish, each step strictly regulated by their respective Guild. Now, in a Manufactory, one person only worked on one part of the final item, which sped up the process immensely and made goods much cheaper. When the industrial revolution kicked off, the manufacturies began making use of machines and their name had been shortened to merely "factory". This isn't 100% accurate (as any historian will point out) but it is, from what I understand, what a manufactory is.