This document discusses parametric design and how it connects code with computer numerical control (CNC) machines and 3D printers. Parametric design uses 3D modeling software and scripting languages to leverage algorithms for repetition and recursion in design. Digital fabrication plays a role in parametric design by joining architecture, product design, manufacturing, and construction through the use of 3D modeling and CNC machines like CNC routers, laser cutters, and high force knife cutters. These machines can accurately fabricate digital models by reading code that represents CNC functions.