The NPD process begins with an idea for a new product which can come from one of several sources. Most often it comes from marketing which developed the idea through its interaction with customers and is often referred to as the voice of the customer When a new product is identified in this manner it is often called market pull which refers to the primary force driving its development. In other words the customer's identified need for the product in the market i pulling it from the firm. The other major method for generating new products is called technology push In this case the customers are not even aware of the need for the product rather it is developed by the company's R&D function and pushed through the company to the marketplace. Polaroid cameras and 3M's Post-it notes provide good examples of new products that were the result of technology push. It is important to note that products resulting from technology push also must have a market need in order for them to be successful. (Polaroid's instant movie system provides a good example of a technology push product for which there was no demand.) At the same time while technology push products tend to be less common than market pull products most breakthrough and radical products are the result of technology push.