Lecture at ICTAC School 2021: 18th International Colloquium on Theoretical Aspects of Computing, Nazarbayev University, Nur-Sultan, Kazakhstan, 1st September 2021. https://www.alandix.com/academic/talks/ICTCS-School-2021/ The first part of this lecture gives a lightning introduction to the use of formal methods in human–computer interaction. This will include an overview of the kinds of models, and typical domains where technqiues are currently applied. It will then outline some of the potential future directions for the field based on the “Trends and Gaps” chaper of “The Handbook of Formal Methods in Human-Computer Interaction”.