Topological materials are materials with unusual properties due to the arrangement of their lattice structure. These materials are characterized by topological invariants, which are stable under certain deformations, meaning that the arrangement of atoms in the material is resistant to change. Topological materials display a variety of physical properties such as conducting electricity with very little resistance, and having unique mechanical properties such as being extremely hard but also very flexible. Examples of topological materials include graphene, topological insulators, and Weyl semimetals.