**3. Future**

Rapid growth in telecommunications and electronics requires development of new and original metamaterial-based and (or) metamaterial-inspired devices. Recently, digital metamaterials and programmable metasurfaces have attracted a lot of attention. Programmable metasurfaces are versatile tools for controlling electromagnetic wave propagation and performing almost instantaneous operations on the wavefronts of passing electromagnetic waves. It is without doubt that the metamaterial concepts (including the ones presented in this Special Issue) will be further developed for such applications.

Telecommunications in the mm-wave and THz bands will bring new challenges that will be addressed, in particular, by making use of materials with exotic electronic properties such as the graphene. In the last few years, topological metamaterials and effects have added an entirely new dimension to the whole picture. Emerging artificial intelligence techniques already assist researchers in design of novel metamaterials and devices based on them. Overall, I believe that there is a bright future for these new technologies and their applications in *engineering metamaterials*.

**Acknowledgments:** Here, first of all, I would like to thank all the Special Issue authors for their valuable contributions and acknowledge the work of anonymous reviewers and the editorial board of *Electronics*. Without your effort this Special Issue could not become a reality! The work related to Guest Editing of this Special Issue and publication of this Editorial was funded by FCT/MCTES, Portugal, through national funds and when applicable co-funded by EU funds under the project UIDB/50008/2020-UIDP/50008/2020.

**Conflicts of Interest:** The author declares no conflict of interest.
