Wikipedia
OV-chipkaart
The OV-chipkaart (short for openbaar vervoer chipkaart, meaning public transport chipcard) is a contactless smart card system used for all public transport in the Netherlands. First introduced in the Rotterdam metro in April 2005, it has subsequently been rolled out to other areas and travel modes. It fully replaced the national strippenkaart system for buses, trams and metros in 2011 and the paper ticket system for rail travel in July 2014.
The OV-chipkaart is available in disposable form (for occasional passengers, such as tourists) and reusable versions (for frequent travellers, either in anonymous or personalized forms).