Rapid prototyping is a set of industrial processes aimed at achieving the so-called prototype.
Regardless of how it is realized, prototype is defined as 'the first element of the series'. They may cover conceptual, functional, technical or pre-series needs, in any case they play different roles in the company: they can be used to assess costs, cycle times, market response and so on.

Some of the most commmon techniques:
 Stereolithography and technique POLYJET