The article reviews the analytical framework for studying the percolation properties of interacting networks, particularly 'networks of networks' formed by interdependent random networks. It highlights the importance of understanding the robustness of these systems, as they are increasingly interconnected in various critical infrastructures. The authors discuss the differences between isolated and interdependent networks, emphasizing that the failure of nodes in one network can lead to cascading failures in others, causing significant damage. They present a generating-function formalism to analyze percolation in two interdependent networks and extend it to a system of \( n \) interacting networks (a network of networks, or NON). The framework reveals that while a single network exhibits a second-order phase transition, the percolation transition in a NON becomes first-order, indicating a more fragile system. The article also explores the robustness of scale-free networks in interdependent systems, noting that their robustness can be enhanced by increasing the fraction of autonomous nodes, designing dependence links to connect nodes with similar degrees, and protecting high-degree nodes. Finally, it outlines future research directions, including the study of real-world interdependent systems and the influence of spatial constraints on network robustness.The article reviews the analytical framework for studying the percolation properties of interacting networks, particularly 'networks of networks' formed by interdependent random networks. It highlights the importance of understanding the robustness of these systems, as they are increasingly interconnected in various critical infrastructures. The authors discuss the differences between isolated and interdependent networks, emphasizing that the failure of nodes in one network can lead to cascading failures in others, causing significant damage. They present a generating-function formalism to analyze percolation in two interdependent networks and extend it to a system of \( n \) interacting networks (a network of networks, or NON). The framework reveals that while a single network exhibits a second-order phase transition, the percolation transition in a NON becomes first-order, indicating a more fragile system. The article also explores the robustness of scale-free networks in interdependent systems, noting that their robustness can be enhanced by increasing the fraction of autonomous nodes, designing dependence links to connect nodes with similar degrees, and protecting high-degree nodes. Finally, it outlines future research directions, including the study of real-world interdependent systems and the influence of spatial constraints on network robustness.