In this section, we put forth a set of potential characteristics for an ideal fast ion conductor based on our comprehensive understanding of various material classes and the underlying theoretical advancements in fast ion conduction. In order to explore these features, we have classified the materials from both the cationic and anionic perspectives, recognizing the pivotal role played by the immobile framework in facilitating mobile ion conduction. Firstly, it is generally observed that stable lattice sites exhibit higher coordination environments. Consequently, these sites foster stronger interactions, resulting in deeper energy minima, as depicted in Fig. . However, it is important to note that such deeper energy minima can also give rise to larger migration energy barriers, impeding cationic diffusion. Conversely, if we design a crystal structure wherein the coordination number along the ion migration path remains relatively constant, we can achieve a flatter energy landscape that facilitates faster ionic diffusion. Secondly, the presence of a three-dimensional ion migration path is crucial for achieving fast ion conduction. This architectural arrangement minimizes the probability of ion transport blockages due to the presence of grain boundaries. Thirdly, it has been established that the concentration of mobile ions directly affects ion conduction, as evident in the conduction equation. However, it is worth highlighting that both mobile ion concentration and vacancies play significant roles in this context. Therefore, the optimal concentration of mobile ions can provide the ideal vacancy concentration, ultimately leading to enhanced ionic conductivity. Fourthly, ion-ion correlation can also significantly reduce the activation energy barrier. Another important factor is anion rotation, which can introduce structural frustration, enabling a flatter energy landscape for faster cationic diffusion.