1) What exactly are airlines?

For air transport services, airlines are companies that provide the services. These services are for the passengers and freight. Some airlines own their specific aircraft, but most of them lease it. It is very beneficial for different airlines to form partnerships for mutual benefit.

Official airlines are recognized by a specific air operating certificate issued by the governmental authorities of the area.

There are allot different types of Airlines. From single aircrafts carrying mail/cargo, to full-service international airlines working with hundreds of aircrafts. The different services can be categorized as: intercontinental, intra-continental, regional, domestic, or international. They are operated as either scheduled services or charters.