Barrier to Entry

Any impediment that prevents new firms from entering an industry and competing on an equal basis with existing firms

Patent

A legal barrier to entry that grants its holder the exclusive right to sell a product for 20 years from the date the patent application is filed. (Pharmaceuticals)

Innovation

The process of turning an innovation into a marketable product

Economies of Scale

Sometimes a monopoly occurs when a firm experiences _____________, as reflected by a downward sloping, long run average cost curve

De Beers

Company that coined the term "Diamonds are Forever", and completely controlled the diamond market in the world - had a monopoly on the market