Ticket resale is the act of reselling tickets for admission

Ticket (admission)

A ticket is a voucher that indicates that one has paid for admission to an event or establishment such as a theatre, movie theater, amusement park, zoo, museum, concert, or other attraction, or permission to travel on a vehicle such as an airliner, train, bus, or boat, typically because one has...

 to events. Tickets are bought from licensed sellers and are then sold for a price determined by the individual or company in possession of the tickets. Tickets sold through secondary sources may be sold for less or more than their face value depending on demand, which itself tends to vary as the event date approaches. When the supply of tickets for a given event available through authorized ticket sellers is depleted, the event is considered "sold out", generally increasing the market value for any tickets on offer through secondary sellers.