Consumers too are certainly a major constraint on firms. In fact, it is ultimately consumers who effectively determine the way in which markets behave – whether they grow or decline and how fast they change. Consumers will evan condition how quickly products are developed and improved in markets. How do they do they do this? Later today if you buy a CD you are entering a market as a consumer but you would hardly perceive yourself as a major player in the music business. And this is true: on its own, your interest in john Lennon or Boyzone doesn’t count for much. However, expressed collectively, purchasing power is the most powerful force at work in any market. It people decide that john Lennon ‘ s songs have begun to sound a little twee and Boyzone are a bit old, then the firms that produce and sell their CDs will focus their efforts upon other more popular or potentially more popular artists.