The invention of the airplane quite literally changed how we live in the world today. Major improvements happened in the field of aviation technology during the two World Wars. After the Second World War, commercial flight routes were established in Europe, and now travelling via flights is so common that you will find it difficult to imagine your life without it. Today the aviation industry is a very competitive market. Most of the countries, including the US, have airlines that are owned privately.
Some of the major factors that affect the aviation industry are the capacity of airports, the structure of the routes, and the money it takes to lease out or rent aircrafts. Weather is another major factor as it is quite unpredictable and can have adverse effects at times. Bad weather can lead to cancellation of flights which results in a loss of lot of money for the airlines.
Fuel is also a major factor as it is the second largest contributor in an airline's expenditure. The efficiency of fuel usage varies among different companies. Carriers with short trips have lesser efficiency as a lot of fuel is spend on landing and take offs.
The largest source of revenue for carriers is through regular and business class passengers. Business passengers are important because they are more likely to use the services again. Transporting cargo and selling frequent flier miles are other ways of earning revenue. | 
