Abstract: Crystals with layered structures have recently attracted tremendous research interest. In these materials, individual layers are held together by relatively weak van der Waals interactions and can be exfoliated into atomically thin sheets. A variety of metastable stacking configurations can emerge in such systems, which can be further exploited to tune their physical properties through twistronics and slidetronics. In this seminar, I will present our recent efforts to identify and engineer stacking geometries in various types of van der Waals crystals. Transmission electron microscopy (TEM), combined with complementary characterization techniques, enables layer-by-layer investigation of interlayer stacking configurations. Representative examples—including CrI₃, γ-GeSe, GdTe₃, and GeSe₂—will be discussed. The seminar will also highlight the roles of stacking faults, temperature-dependent structural transitions, strain-induced effects, and rotational-twin-driven twisting, providing insights into the rich configurational landscape and its implications for accurate structural characterization of layered materials.