Editing Barriers to entry (section)

==Classification and examples==
[[Michael Porter]] classifies the markets into four general cases {{citation needed|date=April 2015}}:

* High barrier to entry and high [[barriers to exit|exit barrier]] (for example, [[telecommunications]], [[Energy industry|energy]])
* High barrier to entry and low exit barrier (for example, [[Consultant|consulting]], [[education]])
* Low barrier to entry and high exit barrier (for example, [[hotel]]s, [[ironworks]])
* Low barrier to entry and low exit barrier (for example, [[retail]], [[electronic commerce]])

These markets combine the attributes:
* Markets with high entry barriers have few players and thus high [[profit margin]]s.
* Markets with low entry barriers have many players and thus low profit margins.
* Markets with high exit barriers are unstable and not self-regulated, so the profit margins fluctuate very much over time.
* Markets with a low exit barrier are stable and self-regulated, so the profit margins do not fluctuate much over time.

The higher the barriers to entry and exit, the more prone a market tends to be a [[natural monopoly]]. The reverse is also true. The lower the barriers, the more likely the market will become [[perfect competition]].