What different types of monopoly are there? How are they different from each other?

Monopolies for a variety of reasons. There can be different terminology used when discussing the different types, but the concepts are the same and based on the nature of the barriers to entry protecting the firm's monopoly. Here is the more common breakdown of the 4 monopoly types:

• Geographic monopoly. This occurs when there is only one firm supplying the good or service. This is common when a single firm is selling goods within its private property and also in small towns with a small consumer base.
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• Government monopoly. This occurs when a government requires a monopoly by either controlling or running the seller or chartering the single seller. In the US, this is common with tap water, power generation and the Post Office.
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• Technological monopoly. This occurs when a firm is able to produce a product that no other firm can. In some countries, this occurs when a firm is granted a patent or copyright over the good or service. It can also occur when a firm has a secret production process or recipe that no other firm knows.
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• Natural monopoly. This occurs when a single firm can produce the good or service at lower costs than any other firm. Other firms will not enter this market because they know they can not match the cost structure of this monopolist.

There is an alternative framework for describing monopoly types. You can just label them, legal or natural. Legal monopolies would be those that were created by some sort of government action, either from charter, nationalization or granting patents or copyright protection. Natural monopolies would occur without any sort of government action.