Barriers to entry

Thanks to tutor2u for this
http://www.tutor2u.net/economics/blog/topic-of-the-day-barriers-to-entry?utm_medium=email&utm_campaign=Economics%20daily%20digest%20Wed%2010th%20February%202016&utm_content=Economics%20daily%20digest%20Wed%2010th%20February%202016+CID_d550d47ef2ec9456a080732f7465efec&utm_source=CampMonitor&utm_term=Topic%20of%20the%20Day%20Barriers%20to%20Entry%20Our%20economics%20topic%20of%20the%20day%20is%20Barriers%20to%20Entry%20Revise%20this%20key%20concept%20using%20our%20study%20notes%20presentations%20and%20more