Many urban residents these days will find it hard to imagine a life without mobile apps that help us locate a restaurant, hail a cab, or find a subway station—usually in a matter of seconds

Xueman Wang |

  Amina and her family in Dakar, Senegal have a metered private water tap in their yard,   but they don’t use it. (Photo: Sumila Gulyani / World Bank) Amina and her family had recently moved to…

Sumila Gulyani |