Two dimensional (2D) materials are an expanding family of atomically thin materials with unique and unexpected optical and electronic properties that we continue discover each day. These materials are of particular interest because they offer the ultimate in layer-by-layer tailorablity to achieve the desired properties of materials. Moreover, electronic and optical devices produced from 2D materials demonstrate extreme mechanical flexibility, giving rise to new possibilities for technological developments with broad and impactful applications. This class will describe in detail the fundamental properties of this unique class of materials, typical approaches to making and characterizing them, and their applications.