Chemical shifts are very sensitive to the detailed molecular structure around the nucleus of interest; in fact, this sensitivity is one of NMR's strength as a tool for structure determination. Because of this, correlation of exact chemical-shift positions with specific molecular features can be difficult. However, it is possible to define certain regions in which resonances due to particular substructures are likely to appear. Such chemical-shift correlation charts are useful for highlighting possible structural features in your sample. The figures below are for for ¹H and ^13C: