Earlier, rapid prototyping or AM used to be called direct digital manufacturing (DDM). The meaning of DDM was a type of manufacturing that converts a digital file directly into a product. The meaning was not different from the meaning of AM. AM does the same; thus, the term DDM was redundant in the same way as the terms rapid manufacturing, rapid tooling, rapid prototyping, and 3D printing were redundant. The use of DDM then was more to appreciate and emphasize the digital aspect of AM. It was not conveying a new approach other than what AM already was conveying. Its use was more to convey the promise of AM. The meaning of DDM evolved with the advancement of AM. Henceforth, DDM meant a method that is a type of AM that allows many products to be formed. Since AM can design many products, DDM meant a method for mass customization. But many AM processes were not able to fulfill this criterion; DDM inadvertently represented few AM processes. The meaning of DDM in this case again was not different from the meaning of AM. This meaning was more to advertise the production capability of AM rather than initiating a new manufacturing paradigm. Thus, DDM was again redundant.