 Metal halide perovskites are promising materials for optoelectronic applications due to their high efficiency and low cost. However, one of the main challenges associated with their use is the migration of ions within the material, which can lead to degradation of device performance over time. This paper reviews recent research into understanding and controlling the migration of ions in perovskite materials as well as potential applications of this phenomenon. This article was authored by Jean Wook Lee, Selgi Aikim, Junae Mo Yang, and others.