What can we learn about controlling a system solely from its underlying network structure? Here we adapt a recently developed framework for control of networks governed by a broad class of nonlinear dynamics that includes the major dynamic models of biological, technological, and social processes. This feedback-based framework provides realizable node overrides that steer a system toward any of its natural long-term dynamic behaviors, regardless of the specific functional forms and system parameters. We use this framework on several real networks, identify the topological characteristics that underlie the predicted node overrides, and compare its predictions to those of structural controllability in control theory. Finally, we demonstrate this framework's applicability in dynamic models of gene regulatory networks and identify nodes whose override is necessary for control in the general case but not in specific model instances.network control | nonlinear dynamics | biological networks | complex networks C ontrolling the internal state of complex systems is of fundamental interest and enables applications in biological, technological, and social contexts. An informative abstraction of these systems is to represent the system's elements as nodes and their interactions as edges of a network. Often asked questions related to control of a networked system are how difficult to control it is, and which network elements need to be controlled, and through which control actions, to drive the system toward a desired control objective (1-11). Among control frameworks, structure-based methods distinguish themselves due to their ability to draw dynamical conclusions based solely on network structure and a general assumption about the type of allowed dynamics. For example, structural controllability (SC), which assumes unspecified linear dynamics or linearized nonlinear dynamics, allows the identification of the minimal number of nodes whose receiving an external signal u(t) drives the system into a state of interest (12, 13).Despite its success and widespread application (14-18), SC may give an incomplete view of the network control properties of a system. In the case of systems with nonlinear dynamics, it provides sufficient conditions to control the system in the neighborhood of a trajectory or a steady state (refs. 1 and 18 and SI Appendix), and its definition of control (full control; from any initial to any final state) does not always match the meaning of control in biological, technological, and social systems, in which control tends to involve only naturally occurring system states (19). In addition to the approaches provided by nonlinear control theory (9-11, 18), new methods of network control have been proposed to incorporate the inherent nonlinear dynamics of real systems and relax the definition of full control (4,6,11,18,20). Only one of these methods, namely, feedback vertex set control (FC), can be reliably applied to large complex networks in which only the structure is well known and the functional form of ...