Invited for this month's cover is the group of Prof. Eike G. Hübner at Fraunhofer Heinrich Hertz Institute HHI, Goslar and Clausthal University of Technology, Clausthal-Zellerfeld, Germany. The cover picture shows a titanium plate, on which the crystal structure (golden circle=Ti, blue circle=O/N/C) of isomorphous TiO, TiN or TiC, respectively, has been engraved by a high-power high pulse repetition rate femtosecond laser process. The process allows for a fast and spatially resolved surface transformation of titanium to golden TiN, blue TiO/TiO2 or black TiC in an atmosphere of nitrogen, air or ethene/argon. The background represents a typical surface microstructure of these interstitial compounds obtained during this transformation. Read the full text of the article at 10.1002/cplu.202100118.