If you travel a lot for business you might need the services of a jet on a moment's notice, or greater control over where you fly to than a commercial airline could provide. One option is to buy your own jet, but that gets very expensive in a hurry and could easily cost several million dollars a year.
A couple of less expensive options are fractional ownership and charter type arrangements. With these you still have the use of a private jet, but at a lower cost. Fractional ownership and charters have positives and negatives, and your situation could dictate which is best..
In very general terms, if you fly less than 100 hours per year, a charter might be best, and if you fly between 100 and 200 hours per year, fractional ownership would be the best option.
In a fractional ownership you purchase a portion of an individual aircraft for a certain amount of time - usually three to five years. Most of these are operated by a service that owns several jets, so you would have a set number of hours to use on any of the company's jets. This wold give you flexibility to use different types of aircraft for different purposes. The downside is a lack of flexibility in scheduling. There are minimum notice requirements, and there is a contractual term to consider.
Charters eliminate the contract, but still give you access to jets. There is no financial commitment as you are not obligated to anything beyond the one flight you pay for. You basically can call and reserve a flight whenever you want, and then just wait until a flight, or jet, is available. The disadvantage is you may not get to choose the aircraft, or the amenities offered. You most often can still control when the flight takes off, but that assumes a jet is available. Often these are also managed by companies that own several jets for charter services.