Multi-use tickets allow a passenger to travel more than once. These include "return tickets" where the passenger pay for two trips at one time. It also includes period cards allowing travel within a certain area (for instance month cards), or during a given number of days that can be chosen within a longer period of time (for instance eight days within a month). Some transit systems sell tickets (passes) aimed at tourists that allow free or discounted entry at many tourist attractions, typically include zero-fare public transport within a city. Period tickets may be for a particular journey (in both directions), or for a whole network.