▎ 摘　　要

Graphene oxide possesses defects of various kinds. The structure of graphene oxide is reviewed with focus on defects in the sigma-framework of the hexagonal lattice. We clearly distinguish between on-plane functionalization defects and in-plane lattice defects. Moreover, vacancy defects and hole defects are discriminated. In this context, Raman spectroscopy is introduced as a sensitive method for detecting and quantifying defects. Moreover, the visualization of in-plane lattice defects by transmission electron microscopy (TEM) at atomic resolution is introduced. Understanding the type and density of defects in graphene oxide bears the potential for advancing the field of research while considering the specific types of defects as structural motifs.