Raman spectroscopy is a versatile tool used to study the properties of graphene, including the number and orientation of layers, edge types, and effects of perturbations such as electric and magnetic fields, strain, doping, disorder, and functional groups. This review covers the state of the art, future directions, and open questions in Raman spectroscopy of graphene. It discusses essential physical processes, such as resonance types and quantum interference, and updates basic concepts and notations. The review highlights the potential of Raman spectroscopy for studying layered materials beyond graphene, emphasizing its ability to provide structural and electronic information in a fast, non-destructive, and high-resolution manner. The historical development of Raman spectroscopy, including the interpretation of spectra and the identification of peaks, is detailed, along with the effects of defects, edges, and external perturbations. The review also explores the impact of defects and disorder on the Raman spectrum, and how these can be quantified to gain insights into the fundamental properties of graphene and related materials.Raman spectroscopy is a versatile tool used to study the properties of graphene, including the number and orientation of layers, edge types, and effects of perturbations such as electric and magnetic fields, strain, doping, disorder, and functional groups. This review covers the state of the art, future directions, and open questions in Raman spectroscopy of graphene. It discusses essential physical processes, such as resonance types and quantum interference, and updates basic concepts and notations. The review highlights the potential of Raman spectroscopy for studying layered materials beyond graphene, emphasizing its ability to provide structural and electronic information in a fast, non-destructive, and high-resolution manner. The historical development of Raman spectroscopy, including the interpretation of spectra and the identification of peaks, is detailed, along with the effects of defects, edges, and external perturbations. The review also explores the impact of defects and disorder on the Raman spectrum, and how these can be quantified to gain insights into the fundamental properties of graphene and related materials.