  Topology, a mathematical concept, has recently become a popular and truly
transdisciplinary topic encompassing condensed matter physics, solid state
chemistry, and materials science. Since there is a direct connection between
real space, namely atoms, valence electrons, bonds and orbitals, and reciprocal
space, namely bands and Fermi surfaces, via symmetry and topology, classifying
topological materials within a single-particle picture is possible. Currently,
most materials are classified as trivial insulators, semimetals and metals, or
as topological insulators, Dirac and Weyl nodal-line semimetals, and
topological metals. The key ingredients for topology are: certain symmetries,
the inert pair effect of the outer electrons leading to inversion of the
conduction and valence bands, and spin-orbit coupling. This review presents the
topological concepts related to solids from the viewpoint of a solid-state
chemist, summarizes techniques for growing single crystals, and describes basic
physical property measurement techniques to characterize topological materials
beyond their structure and provide examples of such materials. Finally, a brief
outlook on the impact of topology in other areas of chemistry is provided at
the end of the article.
