The NOL card is a pre pay transport card usable on public transport in Dubai, including the Metro and Bus. The tickets for the Dubai Metro are available on a tier based system dependent on how often you would use public transport. You have a choice of four different types of Nol card to choose from. For the tourist, the Red Nol card is the best option. You pre pay, can use it for 10 journeys and it’s valid for 90 days.
The others require photo ID and set up of an e-wallet and are not worth arranging unless you are staying for a long while. You can easily pick up your NOL card from any station, where you can pick up the maps. There are ticket machines at every station and at multiple points in Dubai, including the airport. For more information please refer to the Nol site. nol.ae