  Critical infrastructures form a technological skeleton of our world by
providing us with water, food, electricity, gas, transportation, communication,
banking, and finance. Moreover, as urban population increases, the role of
infrastructures become more vital. In this paper, we adopt a network
perspective and discuss the ever growing need for fundamental interdisciplinary
study of critical infrastructure networks, efficient methods for estimating
their reliability, and cost-effective strategies for enhancing their
resiliency. We also highlight some of the main challenges arising on this way,
including cascading failures, feedback loops, and cross-sector
interdependencies.
