The evolution of air-transport comprises of three main stages
1. Piston engine Propeller driven
2. Gas turbine Propeller driven (Turbo prop)
3. Jet.

The early air taxis were mostly single engine, propeller driven aircraft capable of flying at speeds just a little over the speed of modern automobiles, but could get from point A to point B faster because it went "as the crow flies" or the shortest route. These machines could ferry three to four passengers and their luggage at a maximum speed of around 150 kmph with a total range of around two hours only or 300 kms only. The maximum altitude of flight was 5,000 feet.

Twin engined aircrafts were capable of carrying up to 8 passengers at a speed of 250 kmph with a total range of four hours or 1,000 kms.

Names like Cessna, Piper, and King Air became very popular.When the demand for air taxis increased, so did the competition. Some companies offered air conditioned interiors, music, snacks, reclining seats, and lavatory facilities to woo customers.

Enter the 'Turbo Prop' aircraft driven by gas turbine engines which showed up around mid-forties, just after the world war. These planes could fly faster, higher, and carry more loads.

Single engined planes could carry up to 8 passengers and fly at up 350 kmph over a range of up to 1500 kms, and twin engined planes could carry up to 12 passengers. Maximum altitude flown was 10,000 feet.

Jet aircraft showed up in the late forties. There are three types of Jet aircrafts light, medium, and large. The light jets are ideal for private use it could carry up to 8 people in comfort, at speeds exceeding 500 kmph, with a flying range of up to 1500 kms. The mid-sized twin engined Jets could carry 8 to 12 people, at speeds of 800 kmph, over a distance of up to 2500 kms at a stretch.

The large Jets also known as "Business Jets" can carry up to 20 passengers in comfort over a range of 6000 kms at a stretch, at near sonic speeds.

These jet aircrafts fly faster at higher altitudes, so all the jet aircrafts used "pressurized" and air conditioned cabins resulting in more comfort for the passengers. Further, as the range increased, there was need to increase the crew usually there were two pilots, a navigator, and cabin crew of two for serving food.From a humble beginning of connecting nearby towns and cities, Private Jets can now fly around the world!