Charter, also called air taxi or ad-hoc flights require certification from the associated country's regulating body such as the FAA in the U.S. The regulations are differentiated from typical commercial/passenger service by offering a non-scheduled service. In the U.S. these flights are regulated under FAA Part 135. There are some cases where a charter operator can sell scheduled flights, but only in limited quantities.
A single-entity charter is one in which an individual or company charters a plane and bears the entire cost of the flight, so that the passengers do not pay their own airfare. There is no minimum passenger requirement, since the cost is per flight, not per person. Single-entity charters are typically used for business purposes -- for example, travel to meetings and conferences, incentive travel or VIP leisure travel.
Of course, the cheapest way to fly privately is to have a friend who invites you on their flight. Then there are the semi-private charters like JetSmarter, JetSuiteX and JetClass where you can buy a seat on a scheduled private jet and corporate shuttle flight sharing it with strangers, much like if you were on a commercial airline. You can buy tickets on these flights for under $200 and you do avoid those crowded main airport terminals. However, if you want to have the real deal experience, chartering your own private jet, you are looking at something between $5,000 and up to $20,000 per hour depending on the size of aircraft and routing.
Private charter flights offer a range of advantages for busy professionals, including time-efficiency. From quicker check-ins to faster transit times, private jet hire is the perfect way to fulfil multiple meetings in different cities, carry out several site visits in one day or simply have more of an opportunity to remain productive while travelling.