What are the Importance of product design?

The product design specification (PDS) is a listing of the critical parameters, specifications and requirements for the product you are designing. It is a statement of what the product should be and should do. The PDS is created during the problem definition activity very early in the design process. Much of the product design specification is driven by customer needs. It is intended to show what you are trying to achieve, NOT what you will end up with.