Concept is the earliest stage of a product.

This stage takes an idea and determines its feasibility as a product, by
answering basic questions such as:

- Will it work?
- Will people want it?
- Can it be sold at a profit?

In this stage, proof-of-concept designs are often created. These are typically
stripped down versions of a product or function of a product, used to test
feasibility.

Prrof-of-concept designs are sometimes built with more costly off-the-shelf
components, knowing that in production a custom design will reduce the
product cost.

For more complex designs, computer simulation and modeling is performed.

Where possible in this stage or in the prototype stage, working units are put
into the hands of potential customers as soon as possible.