Infrastructure investments are mostly long-lived, service multiple (current and future) users, and interact with other public infrastructures and private investments. Empirical examples cited in the companion article in this issue, ‘Infrastucture: new findings for New Zealand’, include long-lived road, rail and port investments, telecommunications networks (fibre), water infrastructure and local social amenities. Much of this infrastructure is provided by central or local government, but some is also provided by public (state-owned enterprises) and private commercial enterprises.