Advances in the understanding of nanoscale ionic processes in solid‐state thin films have led to the rapid development of devices based on coupled ionic–electronic effects. For example, ion‐driven resistive‐switching (RS) devices have been extensively studied for future memory applications due to their excellent performance in terms of switching speed, endurance, retention, and scalability. Recent studies further suggest that RS devices are more than just resistors with tunable resistance; instead, they exhibit rich and complex internal ionic dynamics that equip them with native information‐processing capabilities, particularly in the temporal domain. RS effects induced by the migration of different types of ions, often driven by an electric field, are discussed. It is shown that, by taking advantage of the different state variables controlled by the ionic processes, important synaptic functions can be faithfully implemented in solid‐state devices and networks. Recent efforts on improving the controllability of ionic processes to optimize device performance are also discussed, along with new opportunities for material design and engineering enabled by the ability to control ionic processes at the atomic scale.Solid‐state resistive‐switching devices driven by nanoscale ionic processes are reviewed, with the focus on the rich ionic dynamics that enable natural implementation of a range of biological synaptic and neuron functions. Efforts to control ion redistribution at the atomic scale have led to improved device performance, and enabled applications based on reconfigurable nanostructures and materials through controlled ionic processes in solid‐state devices.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151267/1/aelm201900184_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151267/2/aelm201900184.pd
