"Learjet" is the common name for any of a series of small jet aircraft
manufactured by the Canadian
company Bombardier Aerospace
Learjets are commonly used by corporations to transport executives and VIP's in swift order. Sometimes very rich people purchase them as well, for personal transportation. They can actually fly higher and faster than a lot of commercial airliners, some models having a cruising altitude of over 50,000 feet. Most commercial airliners operate at around 37,000 feet.
Learjets also generally have good noise dampening capabilities, making for a quiet ride. They are also less subject to turbulence in long-haul flights, since they fly above most weather systems.