There are two main branches in aviation

1. Military aviation
2. Civil aviation

Military aviation is the use of aviation for defense and hostility. Almost all countries have an air force as a part of their defense establishment.  As we saw earlier, it was military aviation that developed first.

Civil aviation is the use of aviation for everything other than military aviation. It could be further divided into two segments:

1. Scheduled air transport
2. General aviation.

Scheduled air transport usually operates on predetermined schedules over established predetermined routes. In many ways it is similar to other public transport services where the user adopts to the schedule of the service provider. For examples all commercial airlines that provide transport services for passengers and cargo on commercial basis publish their flight schedule. Passengers refer this schedule and make reservations for flights that would take them where they want to go.  Cargo operators use this schedule to plan their own operations to deliver cargo to and from the airport.

The schedule of each airline is part of the global airline schedule that involves thousands of airlines and airports. A lot of things such as the availability of airport slots, air route congestion, passenger demand and usage of fuel have to be taken into account when drawing up the flight schedule by an airline.

General aviation includes all other civil aviation operations that are not included in scheduled air transport. In certain parts of the world, in terms of the number of planes involved, this segment is larger.

Examples of general aviation are chartered flight operations (learn more), private flying, recreational flying, agricultural flying and training flights.