Michael Porter's Five Forces Model - Competition and Market Entry

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Porter's Five Forces Model was developed by Michael Porter between 1960-70; it is a tool to analyze the competitiveness of a business.  It is a useful tool to analyze competitors as well as the business itself, also useful to understand potential competitors when entering a new marketplace or industry.
Applying these factors to an existing business may help it fix some flaws, and develop a clearer plan.
Rivalry Among Existing Firms - These factors are essentially the industry standard; understanding the industry standard will help a new business develop proper practices for dealing with customers and suppliers and interact efficiently in the marketplace with little friction.

Threat of New Entrants - What factors determine whether or not new firms would like to enter a marketplace?  Demand in the marketplace can drive up prices making industries in short supply attractive for new investment; this is one factor.  Understanding many of these conditions and their state in the market may help to reveal attractive new businesses.

Supplier Power - Suppliers are an important aspect to a business which require a lot of materials or services to operate.  These determining factors may affect a business more or less depending on the type of business it is.

Buyer Power - Similar to supplier power, customers of a product or service may have significant influence over a business.  Customers may be other firms which have the potential to purchase a supplier if is considered economic.

Threat of Substitutes - Substitute products and services can become much more attractive to customers depending on the state of the economy; given local price levels and wage rates, or other factors.

Using an existing or new business idea, develop an analysis using Porter's Five Forces Model;  it may help to reveal new ideas, or a new understanding of a business.