Prototype
A prototype is an early version of a planned product that is created before series production begins. It serves to visualise the product concept and to test its functionality. Essentially, a prototype is a practical sample or model that serves to illustrate the planned end product and to check key aspects such as design, functionality, ergonomics and user-friendliness.
By developing and testing a prototype, engineers, designers and other parties involved can gain valuable insights that help to improve the final product before it goes into mass production.