History
One important force that Porter describes is the degree of rivalry between existing companies in the market. If there are more companies competing with each other, the resulting competitive pressure will mean that prices, profits and strategy will be driven by it.
One company may end up having little or no power in its own industry if there is a variety of quality products are offered in the market in direct competition with it. Customers have the option of simply moving on to a different company easily. Conversely, in the absence of this rivalry, the company may be able to freely set prices and profit margins without being dictated by what the customer finds attractive.
much altered world, it remains one of the most widely used methods of industry analysis.