Graphene, a two-dimensional carbon allotrope, has unique electronic and phonon properties that can be studied experimentally. Its Raman spectrum uniquely captures its electronic structure and evolves with the number of layers. This allows for unambiguous, high-throughput, non-destructive identification of graphene layers, which is critical in this emerging field. The study shows that Raman fingerprints for single-, bi- and few-layer graphene reflect changes in the electronic structure and electron-phonon interactions. Graphene can be obtained via micro-mechanical cleavage of graphite. The study uses Transmission Electron Microscopy (TEM) to confirm the number of layers in samples. The Raman spectra of single, bi and multi-layer graphene show distinct features. The 2D peak in graphene is a single sharp peak, while in bulk graphite it consists of two components. The 2D peak in bi-layer graphene splits into four components, which is due to the splitting of the electronic bands. The Raman spectrum of graphene is compared with that of bulk graphite and other materials like SWNTs. The 2D peak in graphene is similar to that in SWNTs of 1-2 nm diameter, suggesting that curvature effects are small for this diameter range. The study also shows that the 2D peak in SWNTs splits into two peaks due to confinement and curvature effects. The Raman spectrum of graphene is a powerful tool for identifying the number of layers. The study confirms that Raman spectroscopy can clearly distinguish single-layer, bi-layer, and few-layer graphene. This has important implications for the study and application of graphene in various fields.Graphene, a two-dimensional carbon allotrope, has unique electronic and phonon properties that can be studied experimentally. Its Raman spectrum uniquely captures its electronic structure and evolves with the number of layers. This allows for unambiguous, high-throughput, non-destructive identification of graphene layers, which is critical in this emerging field. The study shows that Raman fingerprints for single-, bi- and few-layer graphene reflect changes in the electronic structure and electron-phonon interactions. Graphene can be obtained via micro-mechanical cleavage of graphite. The study uses Transmission Electron Microscopy (TEM) to confirm the number of layers in samples. The Raman spectra of single, bi and multi-layer graphene show distinct features. The 2D peak in graphene is a single sharp peak, while in bulk graphite it consists of two components. The 2D peak in bi-layer graphene splits into four components, which is due to the splitting of the electronic bands. The Raman spectrum of graphene is compared with that of bulk graphite and other materials like SWNTs. The 2D peak in graphene is similar to that in SWNTs of 1-2 nm diameter, suggesting that curvature effects are small for this diameter range. The study also shows that the 2D peak in SWNTs splits into two peaks due to confinement and curvature effects. The Raman spectrum of graphene is a powerful tool for identifying the number of layers. The study confirms that Raman spectroscopy can clearly distinguish single-layer, bi-layer, and few-layer graphene. This has important implications for the study and application of graphene in various fields.