From Wikipedia:
Product designers are equipped with the skills needed to bring products from conception to market. They should have the ability to manage design projects, and subcontract areas to other sectors of the design industry. Aesthetics is considered important in Product Design but designers also deal with important aspects including technology, ergonomics, usability, stress analysis and materials engineering.
As with most of the design fields the idea for the design of a product arises from a need and has a use. It follows a certain method and can sometimes be attributed to more complex factors such as association and telesis. Also used to describe a technically competent product designer or industrial designer is the term Industrial Design Engineer. The Cyclone vacuum cleaner inventor James Dyson for example could be considered to be in this category (see his autobiography Against The Odds, Pub Thomson 2002).